фикс//

AndDietCokeProject/AndDietCokeBusinessLogic/AndDietCokeBusinessLogic.csproj

@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<TargetFramework>net8.0</TargetFramework>
+		<ImplicitUsings>enable</ImplicitUsings>
+		<Nullable>enable</Nullable>
+	</PropertyGroup>
+
+	<ItemGroup>
+		<InternalsVisibleTo Include="AndDietCokeTests" />
+		<InternalsVisibleTo Include ="DynamicProxyGenAssembly2"/>
+	</ItemGroup>
+	
+	<ItemGroup>
+		<PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="9.0.3" />
+	</ItemGroup>
+
+	<ItemGroup>
+	  <ProjectReference Include="..\AndDietCokeContracts\AndDietCokeContracts.csproj" />
+	</ItemGroup>
+
+</Project>

AndDietCokeProject/AndDietCokeBusinessLogic/Implementations/ClientBusinessLogicContract.cs

@@ -0,0 +1,109 @@
+using AndDietCokeContracts.BusinessLogicsContracts;
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.Extensions;
+using AndDietCokeContracts.StoragesContracts;
+using Microsoft.Extensions.Logging;
+using System.Text.Json;
+using System.Text.RegularExpressions;
+
+namespace AndDietCokeBusinessLogic.Implementations;
+internal class ClientBusinessLogicContract(IClientStorageContract clientStorageContract, ILogger logger) : IClientBusinessLogicsContracts
+{
+    private readonly ILogger _logger = logger;
+    private readonly IClientStorageContract _clientStorageContract = clientStorageContract;
+
+    public List<СlientDataModel> GetAllClients()
+    {
+        _logger.LogInformation("GetAllClients");
+        return _clientStorageContract.GetList() ?? throw new NullListException();
+    }
+
+    public СlientDataModel GetClientByData(string data)
+    {
+        _logger.LogInformation("Get client by data: {data}", data);
+
+        if (data.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(data));
+        }
+
+        if (data.IsGuid())
+        {
+            return _clientStorageContract.GetElementById(data) ??
+                   throw new ElementNotFoundException(data);
+        }
+
+        if (Regex.IsMatch(data, @"^((8|\+7)[\- ]?)?(\(?\d{3}\)?[\- ]?)?[\d\- ]{7,10}$"))
+        {
+            return _clientStorageContract.GetElementByPhoneNumber(data) ??
+                   throw new ElementNotFoundException(data);
+        }
+
+        return _clientStorageContract.GetElementByFIO(data) ??
+               throw new ElementNotFoundException(data);
+    }
+
+    public void InsertClient(СlientDataModel clientDataModel)
+    {
+        _logger.LogInformation("New client data: {json}",
+            JsonSerializer.Serialize(clientDataModel));
+
+        ArgumentNullException.ThrowIfNull(clientDataModel);
+        clientDataModel.Validate();
+
+        try
+        {
+            _clientStorageContract.AddElement(clientDataModel);
+        }
+        catch (ElementExistsException ex)
+        {
+            _logger.LogWarning(ex, "Failed to insert client - already exists");
+            throw;
+        }
+    }
+
+    public void UpdateClient(СlientDataModel clientDataModel)
+    {
+        _logger.LogInformation("Update client data: {json}",
+            JsonSerializer.Serialize(clientDataModel));
+
+        ArgumentNullException.ThrowIfNull(clientDataModel);
+        clientDataModel.Validate();
+
+        try
+        {
+            _clientStorageContract.UpdElement(clientDataModel);
+        }
+        catch (ElementNotFoundException ex)
+        {
+            _logger.LogWarning(ex, "Failed to update client - not found");
+            throw;
+        }
+    }
+
+    public void DeleteClient(string id)
+    {
+        _logger.LogInformation("Delete client by id: {id}", id);
+
+        if (id.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(id));
+        }
+
+        if (!id.IsGuid())
+        {
+            throw new ValidationException("Id is not a unique identifier");
+        }
+
+        try
+        {
+            _clientStorageContract.DelElement(id);
+        }
+        catch (ElementNotFoundException ex)
+        {
+            _logger.LogWarning(ex, "Failed to delete client - not found");
+            throw;
+        }
+    }
+}

AndDietCokeProject/AndDietCokeBusinessLogic/Implementations/DishBusinessLogicContract.cs

@@ -0,0 +1,155 @@
+using AndDietCokeContracts.BusinessLogicsContracts;
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Enums;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.Extensions;
+using AndDietCokeContracts.StoragesContracts;
+using Microsoft.Extensions.Logging;
+using System.Text.Json;
+
+namespace AndDietCokeBusinessLogic.Implementations;
+
+internal class DishBusinessLogicContract(
+    IDishStorageContracts dishStorageContracts,
+    ILogger<DishBusinessLogicContract> logger) : IDishBusinessLogicsContracts
+{
+    private readonly ILogger _logger = logger;
+    private readonly IDishStorageContracts _dishStorageContract = dishStorageContracts;
+
+    public List<DishDataModel> GetAllDishes()
+    {
+        _logger.LogInformation("GetAllDishes called");
+
+        var result = _dishStorageContract.GetList();
+        return result ?? throw new NullListException();
+    }
+
+    public List<DishHistoryDataModel> GetDishHistory(string dishId)
+    {
+        _logger.LogInformation("GetDishHistory called for dishId: {dishId}", dishId);
+
+        if (dishId.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(dishId));
+        }
+
+        if (!dishId.IsGuid())
+        {
+            throw new ValidationException("DishId must be a valid GUID");
+        }
+
+        var result = _dishStorageContract.GetHistoryByProductId(dishId);
+        return result ?? throw new NullListException();
+    }
+
+    public DishDataModel? GetDishById(string id)
+    {
+        _logger.LogInformation("GetDishById called with id: {id}", id);
+
+        if (id.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(id));
+        }
+
+        if (!id.IsGuid())
+        {
+            throw new ValidationException("Id must be a valid GUID");
+        }
+
+        return _dishStorageContract.GetElementById(id)
+            ?? throw new ElementNotFoundException(id);
+    }
+
+    public DishDataModel? GetDishByName(string name)
+    {
+        _logger.LogInformation("GetDishByName called with name: {name}", name);
+
+        if (name.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(name));
+        }
+
+        return _dishStorageContract.GetElementByName(name)
+            ?? throw new ElementNotFoundException(name);
+    }
+
+    public void InsertDish(DishDataModel dishDataModel)
+    {
+        _logger.LogInformation("InsertDish called with data: {data}",
+            JsonSerializer.Serialize(dishDataModel));
+
+        ArgumentNullException.ThrowIfNull(dishDataModel);
+        dishDataModel.Validate();
+
+        // Проверка на уникальность имени
+        var existingByName = _dishStorageContract.GetElementByName(dishDataModel.Name);
+        if (existingByName != null)
+        {
+            throw new ValidationException($"Dish with name '{dishDataModel.Name}' already exists");
+        }
+
+        // Проверка на уникальность ID
+        var existingById = _dishStorageContract.GetElementById(dishDataModel.Id);
+        if (existingById != null)
+        {
+            throw new ValidationException($"Dish with ID {dishDataModel.Id} already exists");
+        }
+
+        _dishStorageContract.AddElement(dishDataModel);
+        _logger.LogInformation("Dish successfully inserted: {id}", dishDataModel.Id);
+    }
+
+    public void UpdateDish(DishDataModel dishDataModel)
+    {
+        _logger.LogInformation("UpdateDish called with data: {data}",
+            JsonSerializer.Serialize(dishDataModel));
+
+        ArgumentNullException.ThrowIfNull(dishDataModel);
+        dishDataModel.Validate();
+
+        // Проверка что блюдо существует
+        var existingDish = _dishStorageContract.GetElementById(dishDataModel.Id);
+        if (existingDish == null)
+        {
+            throw new ElementNotFoundException(dishDataModel.Id);
+        }
+
+        // Проверка на уникальность имени (если имя изменилось)
+        if (!existingDish.Name.Equals(dishDataModel.Name, StringComparison.OrdinalIgnoreCase))
+        {
+            var dishWithSameName = _dishStorageContract.GetElementByName(dishDataModel.Name);
+            if (dishWithSameName != null)
+            {
+                throw new ValidationException($"Dish with name '{dishDataModel.Name}' already exists");
+            }
+        }
+
+        _dishStorageContract.UpdElement(dishDataModel);
+        _logger.LogInformation("Dish successfully updated: {id}", dishDataModel.Id);
+    }
+
+    public void DeleteDish(string id)
+    {
+        _logger.LogInformation("DeleteDish called with id: {id}", id);
+
+        if (id.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(id));
+        }
+
+        if (!id.IsGuid())
+        {
+            throw new ValidationException("Id must be a valid GUID");
+        }
+
+        // Проверка что блюдо существует
+        var existingDish = _dishStorageContract.GetElementById(id);
+        if (existingDish == null)
+        {
+            throw new ElementNotFoundException(id);
+        }
+
+        _dishStorageContract.DelElement(id);
+        _logger.LogInformation("Dish successfully deleted: {id}", id);
+    }
+}

AndDietCokeProject/AndDietCokeBusinessLogic/Implementations/Dish_OrderBusinessLogicContract.cs

@@ -0,0 +1,160 @@
+using AndDietCokeContracts.BusinessLogicsContracts;
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.Extensions;
+using AndDietCokeContracts.StoragesContracts;
+using Microsoft.Extensions.Logging;
+using System.Text.Json;
+
+namespace AndDietCokeBusinessLogic.Implementations;
+
+internal class Dish_OrderBusinessLogicContract(
+    IDish_OrderStorageContract dishOrderStorageContract,
+    ILogger<Dish_OrderBusinessLogicContract> logger) : IDish_OrderBusinessLogicsContracts
+{
+    private readonly ILogger _logger = logger;
+    private readonly IDish_OrderStorageContract _dishOrderStorageContract = dishOrderStorageContract;
+
+    public List<Dish_OrderDataModel> GetAllDishOrders(string? orderId = null, string? dishId = null)
+    {
+        _logger.LogInformation(
+            "GetAllDishOrders called with params: orderId={orderId}, dishId={dishId}",
+            orderId, dishId);
+
+        if (orderId != null && !orderId.IsGuid())
+        {
+            throw new ValidationException("OrderId must be a valid GUID");
+        }
+
+        if (dishId != null && !dishId.IsGuid())
+        {
+            throw new ValidationException("DishId must be a valid GUID");
+        }
+
+        var result = _dishOrderStorageContract.GetList(orderId, dishId);
+
+        return result ?? throw new NullListException();
+    }
+
+    public Dish_OrderDataModel? GetDishOrderById(string orderId, string dishId)
+    {
+        _logger.LogInformation(
+            "GetDishOrderById called with params: orderId={orderId}, dishId={dishId}",
+            orderId, dishId);
+
+        if (orderId.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(orderId));
+        }
+
+        if (!orderId.IsGuid())
+        {
+            throw new ValidationException("OrderId must be a valid GUID");
+        }
+
+        if (dishId.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(dishId));
+        }
+
+        if (!dishId.IsGuid())
+        {
+            throw new ValidationException("DishId must be a valid GUID");
+        }
+
+        return _dishOrderStorageContract.GetElementById(orderId, dishId)
+            ?? throw new ElementNotFoundException($"DishOrder with orderId={orderId} and dishId={dishId} not found");
+    }
+
+    public void InsertDishOrder(Dish_OrderDataModel dishOrderDataModel)
+    {
+        _logger.LogInformation(
+            "InsertDishOrder called with data: {data}",
+            JsonSerializer.Serialize(dishOrderDataModel));
+
+        ArgumentNullException.ThrowIfNull(dishOrderDataModel);
+        dishOrderDataModel.Validate();
+
+        // Проверка на существование записи
+        var existing = _dishOrderStorageContract.GetElementById(
+            dishOrderDataModel.OrderId,
+            dishOrderDataModel.DishId);
+
+        if (existing != null)
+        {
+            throw new ValidationException(
+                $"DishOrder with orderId={dishOrderDataModel.OrderId} and dishId={dishOrderDataModel.DishId} already exists");
+        }
+
+        _dishOrderStorageContract.AddElement(dishOrderDataModel);
+        _logger.LogInformation(
+            "DishOrder successfully inserted: orderId={orderId}, dishId={dishId}",
+            dishOrderDataModel.OrderId, dishOrderDataModel.DishId);
+    }
+
+    public void UpdateDishOrder(Dish_OrderDataModel dishOrderDataModel)
+    {
+        _logger.LogInformation(
+            "UpdateDishOrder called with data: {data}",
+            JsonSerializer.Serialize(dishOrderDataModel));
+
+        ArgumentNullException.ThrowIfNull(dishOrderDataModel);
+        dishOrderDataModel.Validate();
+
+        // Проверка что запись существует
+        var existing = _dishOrderStorageContract.GetElementById(
+            dishOrderDataModel.OrderId,
+            dishOrderDataModel.DishId);
+
+        if (existing == null)
+        {
+            throw new ElementNotFoundException(
+                $"DishOrder with orderId={dishOrderDataModel.OrderId} and dishId={dishOrderDataModel.DishId} not found");
+        }
+
+        _dishOrderStorageContract.UpdElement(dishOrderDataModel);
+        _logger.LogInformation(
+            "DishOrder successfully updated: orderId={orderId}, dishId={dishId}",
+            dishOrderDataModel.OrderId, dishOrderDataModel.DishId);
+    }
+
+    public void DeleteDishOrder(string orderId, string dishId)
+    {
+        _logger.LogInformation(
+            "DeleteDishOrder called with params: orderId={orderId}, dishId={dishId}",
+            orderId, dishId);
+
+        if (orderId.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(orderId));
+        }
+
+        if (!orderId.IsGuid())
+        {
+            throw new ValidationException("OrderId must be a valid GUID");
+        }
+
+        if (dishId.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(dishId));
+        }
+
+        if (!dishId.IsGuid())
+        {
+            throw new ValidationException("DishId must be a valid GUID");
+        }
+
+        // Проверка что запись существует
+        var existing = _dishOrderStorageContract.GetElementById(orderId, dishId);
+        if (existing == null)
+        {
+            throw new ElementNotFoundException(
+                $"DishOrder with orderId={orderId} and dishId={dishId} not found");
+        }
+
+        _dishOrderStorageContract.DelElement(orderId, dishId);
+        _logger.LogInformation(
+            "DishOrder successfully deleted: orderId={orderId}, dishId={dishId}",
+            orderId, dishId);
+    }
+}

AndDietCokeProject/AndDietCokeBusinessLogic/Implementations/EmployeeBusinessLogicContract.cs

@@ -0,0 +1,144 @@
+using AndDietCokeContracts.BusinessLogicsContracts;
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Enums;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.Extensions;
+using AndDietCokeContracts.StoragesContracts;
+using Microsoft.Extensions.Logging;
+using System.Text.Json;
+
+namespace AndDietCokeBusinessLogic.Implementations;
+
+internal class EmployeeBusinessLogicContract(
+    IEmployeeStoragesContracts employeeStoragesContracts,
+    ILogger<EmployeeBusinessLogicContract> logger) : IEmployeeBusinessLogicsContracts
+{
+    private readonly ILogger _logger = logger;
+    private readonly IEmployeeStoragesContracts _employeeStorageContract = employeeStoragesContracts;
+
+    public List<EmployeeDataModel> GetAllEmployees(
+        bool onlyActive = true,
+        string? positionId = null,
+        DateTime? fromBirthDate = null,
+        DateTime? toBirthDate = null,
+        DateTime? fromEmploymentDate = null,
+        DateTime? toEmploymentDate = null)
+    {
+        _logger.LogInformation(
+            "GetAllEmployees params: onlyActive={onlyActive}, positionId={positionId}, " +
+            "fromBirthDate={fromBirthDate}, toBirthDate={toBirthDate}, " +
+            "fromEmploymentDate={fromEmploymentDate}, toEmploymentDate={toEmploymentDate}",
+            onlyActive, positionId, fromBirthDate, toBirthDate, fromEmploymentDate, toEmploymentDate);
+
+        if (positionId != null && positionId.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(positionId));
+        }
+
+        if (positionId != null && !positionId.IsGuid())
+        {
+            throw new ValidationException("The value in the field positionId is not a unique identifier.");
+        }
+
+        if (fromBirthDate.HasValue && toBirthDate.HasValue && fromBirthDate > toBirthDate)
+        {
+            throw new IncorrectDatesException(fromBirthDate.Value, toBirthDate.Value);
+        }
+
+        if (fromEmploymentDate.HasValue && toEmploymentDate.HasValue && fromEmploymentDate > toEmploymentDate)
+        {
+            throw new IncorrectDatesException(fromEmploymentDate.Value, toEmploymentDate.Value);
+        }
+
+        var result = _employeeStorageContract.GetList(
+            onlyActive,
+            positionId,
+            fromBirthDate,
+            toBirthDate,
+            fromEmploymentDate,
+            toEmploymentDate);
+
+        return result ?? throw new NullListException();
+    }
+
+    public EmployeeDataModel? GetEmployeeById(string id)
+    {
+        _logger.LogInformation("GetEmployeeById params: {id}", id);
+
+        if (id.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(id));
+        }
+
+        if (!id.IsGuid())
+        {
+            throw new ValidationException("The value in the field id is not a unique identifier.");
+        }
+
+        return _employeeStorageContract.GetElementById(id) ?? throw new ElementNotFoundException(id);
+    }
+
+    public EmployeeDataModel? GetEmployeeByFIO(string fio)
+    {
+        _logger.LogInformation("GetEmployeeByFIO params: {fio}", fio);
+
+        if (fio.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(fio));
+        }
+
+        return _employeeStorageContract.GetElementByFIO(fio) ?? throw new ElementNotFoundException(fio);
+    }
+
+    public void InsertEmployee(EmployeeDataModel employeeDataModel)
+    {
+        _logger.LogInformation("InsertEmployee params: {json}", JsonSerializer.Serialize(employeeDataModel));
+
+        ArgumentNullException.ThrowIfNull(employeeDataModel);
+        employeeDataModel.Validate();
+
+        if (_employeeStorageContract.GetElementById(employeeDataModel.Id) != null)
+        {
+            throw new DuplicateEmployeeException(employeeDataModel.Id);
+        }
+
+        _employeeStorageContract.AddElement(employeeDataModel);
+    }
+
+    public void UpdateEmployee(EmployeeDataModel employeeDataModel)
+    {
+        _logger.LogInformation("UpdateEmployee params: {json}", JsonSerializer.Serialize(employeeDataModel));
+
+        ArgumentNullException.ThrowIfNull(employeeDataModel);
+        employeeDataModel.Validate();
+
+        if (_employeeStorageContract.GetElementById(employeeDataModel.Id) == null)
+        {
+            throw new ElementNotFoundException(employeeDataModel.Id);
+        }
+
+        _employeeStorageContract.UpdElement(employeeDataModel);
+    }
+
+    public void DeleteEmployee(string id)
+    {
+        _logger.LogInformation("DeleteEmployee params: {id}", id);
+
+        if (id.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(id));
+        }
+
+        if (!id.IsGuid())
+        {
+            throw new ValidationException("The value in the field id is not a unique identifier.");
+        }
+
+        if (_employeeStorageContract.GetElementById(id) == null)
+        {
+            throw new ElementNotFoundException(id);
+        }
+
+        _employeeStorageContract.DelElement(id);
+    }
+}

AndDietCokeProject/AndDietCokeBusinessLogic/Implementations/OrderBusinessLogicContract.cs

@@ -0,0 +1,105 @@
+using AndDietCokeContracts.BusinessLogicsContracts;
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.Extensions;
+using AndDietCokeContracts.StorageContracts;
+using Microsoft.Extensions.Logging;
+using System.Text.Json;
+
+namespace AndDietCokeBusinessLogic.Implementations;
+
+internal class OrderBusinessLogicContract(
+    IOrderStorageContracts orderStorageContract,
+    ILogger<OrderBusinessLogicContract> logger) : IOrderBusinessLogicsContracts
+{
+    private readonly ILogger _logger = logger;
+    private readonly IOrderStorageContracts _orderStorageContract = orderStorageContract;
+
+    public List<OrderDataModels> GetAllOrders(string? clientId = null, string? employeedId = null, string? dishId = null)
+    {
+        _logger.LogInformation(
+            "GetAllOrders called with filters - ClientId: {clientId}, EmployeeId: {employeedId}, DishId: {dishId}",
+            clientId, employeedId, dishId);
+
+        // Валидация параметров фильтрации
+        if (clientId != null && !clientId.IsGuid())
+        {
+            throw new ValidationException("ClientId must be a valid GUID");
+        }
+
+        if (employeedId != null && !employeedId.IsGuid())
+        {
+            throw new ValidationException("EmployeeId must be a valid GUID");
+        }
+
+        if (dishId != null && !dishId.IsGuid())
+        {
+            throw new ValidationException("DishId must be a valid GUID");
+        }
+
+        var result = _orderStorageContract.GetList(clientId, employeedId, dishId);
+        return result ?? throw new NullListException();
+    }
+
+    public OrderDataModels? GetOrderById(string id)
+    {
+        _logger.LogInformation("GetOrderById called with id: {id}", id);
+
+        if (id.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(id));
+        }
+
+        if (!id.IsGuid())
+        {
+            throw new ValidationException("OrderId must be a valid GUID");
+        }
+
+        var order = _orderStorageContract.GetElementById(id);
+        return order ?? throw new ElementNotFoundException($"Order with id {id} not found");
+    }
+
+    public void InsertOrder(OrderDataModels orderDataModel)
+    {
+        _logger.LogInformation("InsertOrder called with data: {data}",
+            JsonSerializer.Serialize(orderDataModel));
+
+        ArgumentNullException.ThrowIfNull(orderDataModel);
+        orderDataModel.Validate();
+
+        // Проверка на существование заказа с таким ID
+        var existingOrder = _orderStorageContract.GetElementById(orderDataModel.Id);
+        if (existingOrder != null)
+        {
+            throw new ValidationException($"Order with id {orderDataModel.Id} already exists");
+        }
+
+        _orderStorageContract.AddElement(orderDataModel);
+        _logger.LogInformation("Order successfully created with id: {id}", orderDataModel.Id);
+    }
+
+    public void DeleteOrder(string id)
+    {
+        _logger.LogInformation("DeleteOrder called for id: {id}", id);
+
+        if (id.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(id));
+        }
+
+        if (!id.IsGuid())
+        {
+            throw new ValidationException("OrderId must be a valid GUID");
+        }
+
+        // Проверка что заказ существует
+        var existingOrder = _orderStorageContract.GetElementById(id);
+        if (existingOrder == null)
+        {
+            throw new ElementNotFoundException($"Order with id {id} not found");
+        }
+
+        _orderStorageContract.DelElement(id);
+        _logger.LogInformation("Order successfully deleted with id: {id}", id);
+    }
+}

AndDietCokeProject/AndDietCokeBusinessLogic/Implementations/PositionBusinessLogicContract.cs

@@ -0,0 +1,103 @@
+using AndDietCokeContracts.BusinessLogicsContracts;
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Enums;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.Extensions;
+using AndDietCokeContracts.StoragesContracts;
+using Microsoft.Extensions.Logging;
+using System.Text.Json;
+
+namespace AndDietCokeBusinessLogic.Implementations;
+
+internal class PositionBusinessLogicContract(IPositionStorageContract positionStorageContract, ILogger logger)
+    : IPositionBusinessLogicsContracts
+{
+    private readonly ILogger _logger = logger;
+    private readonly IPositionStorageContract _positionStorageContract = positionStorageContract;
+
+    public List<PositionDataModel> GetAllPositions(bool onlyActive = true)
+    {
+        _logger.LogInformation("GetAllPositions params: {onlyActive}", onlyActive);
+        return _positionStorageContract.GetList(onlyActive) ?? throw new NullListException();
+
+    }
+
+    public List<PositionDataModel> GetAllDataOfPosition(string positionId)
+    {
+        _logger.LogInformation("GetAllDataOfPost for {postId}", positionId);
+        if (positionId.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(positionId));
+        }
+        if (!positionId.IsGuid())
+        {
+            throw new ValidationException("The value in the field postId is not a unique identifier.");
+        }
+        return _positionStorageContract.GetPostWithHistory(positionId) ?? throw new NullListException();
+    }
+
+    public PositionDataModel GetPositionByData(string data)
+    {
+        _logger.LogInformation("Get element by data: {data}", data);
+        if (data.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(data));
+        }
+
+        PositionDataModel position;
+        if (data.IsGuid())
+        {
+            position = _positionStorageContract.GetElementById(data);
+        }
+        else
+        {
+            position = _positionStorageContract.GetElementByName(data);
+        }
+
+        return position ?? throw new ElementNotFoundException(data);
+    }
+
+    public void InsertPosition(PositionDataModel positionDataModel)
+    {
+        _logger.LogInformation("New data: {json}", JsonSerializer.Serialize(positionDataModel));
+        ArgumentNullException.ThrowIfNull(positionDataModel);
+        positionDataModel.Validate();
+        _positionStorageContract.AddElement(positionDataModel);
+    }
+
+    public void UpdatePosition(PositionDataModel positionDataModel)
+    {
+        _logger.LogInformation("Update data: {json}", JsonSerializer.Serialize(positionDataModel));
+        ArgumentNullException.ThrowIfNull(positionDataModel);
+        positionDataModel.Validate();
+        _positionStorageContract.UpdElement(positionDataModel);
+    }
+
+    public void DeletePosition(string id)
+    {
+        _logger.LogInformation("Delete by id: {id}", id);
+        if (id.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(id));
+        }
+        if (!id.IsGuid())
+        {
+            throw new ValidationException("Id is not a unique identifier");
+        }
+        _positionStorageContract.DelElement(id);
+    }
+
+    public void RestorePosition(string id)
+    {
+        _logger.LogInformation("Restore by id: {id}", id);
+        if (id.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(id));
+        }
+        if (!id.IsGuid())
+        {
+            throw new ValidationException("Id is not a unique identifier");
+        }
+        _positionStorageContract.ResElement(id);
+    }
+}

AndDietCokeProject/AndDietCokeBusinessLogic/Implementations/SalaryBusinessLogicContract.cs

@@ -0,0 +1,65 @@
+using AndDietCokeContracts.BusinessLogicsContracts;
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.Extensions;
+using AndDietCokeContracts.StorageContract;
+using Microsoft.Extensions.Logging;
+
+internal class SalaryBusinessLogicContract(ISalaryStorageContract salaryStorageContract, ILogger logger) : ISalaryBusinessLogicsContracts
+{
+    private readonly ILogger _logger = logger;
+    private readonly ISalaryStorageContract _salaryStorageContract = salaryStorageContract;
+
+    public List<SalaryDataModel> GetAllSalariesByPeriod(DateTime fromDate, DateTime toDate)
+    {
+        _logger.LogInformation("GetAllSalariesByPeriod params: {fromDate}, {toDate}", fromDate, toDate);
+
+        if (fromDate.IsDateNotOlder(toDate))
+        {
+            throw new IncorrectDatesException(fromDate, toDate);
+        }
+
+        return _salaryStorageContract.GetList(fromDate, toDate) ?? throw new NullListException();
+    }
+
+    public List<SalaryDataModel> GetAllSalariesByPeriodByEmployee(DateTime fromDate, DateTime toDate, string employeeId)
+    {
+        _logger.LogInformation("GetAllSalariesByPeriodByEmployee params: {fromDate}, {toDate}, {employeeId}",
+            fromDate, toDate, employeeId);
+
+        if (fromDate.IsDateNotOlder(toDate))
+        {
+            throw new IncorrectDatesException(fromDate, toDate);
+        }
+
+        if (employeeId.IsEmpty())
+        {
+            throw new ArgumentNullException(nameof(employeeId));
+        }
+
+        if (!employeeId.IsGuid())
+        {
+            throw new ValidationException("The value in the field employeeId is not a unique identifier.");
+        }
+
+        return _salaryStorageContract.GetList(fromDate, toDate, employeeId) ?? throw new NullListException();
+    }
+
+    public void CalculateSalaryByMonth(DateTime date)
+    {
+        _logger.LogInformation("CalculateSalaryByMonth: {date}", date);
+
+        var startDate = new DateTime(date.Year, date.Month, 1);
+        var endDate = new DateTime(date.Year, date.Month, DateTime.DaysInMonth(date.Year, date.Month));
+
+        // Get all salaries for the month to avoid duplicate calculations
+        var existingSalaries = _salaryStorageContract.GetList(startDate, endDate);
+
+        if (existingSalaries != null && existingSalaries.Any())
+        {
+            _logger.LogWarning("Salaries for period {startDate} to {endDate} already exist", startDate, endDate);
+            return;
+        }
+
+    }
+}

AndDietCokeProject/AndDietCokeContracts/BusinessLogicsContracts/IClientBusinessLogicsContrats.cs

@@ -0,0 +1,16 @@
+using AndDietCokeContracts.DataModels;
+
+namespace AndDietCokeContracts.BusinessLogicsContracts;
+
+public interface IClientBusinessLogicsContracts
+{
+    List<СlientDataModel> GetAllClients();
+
+    СlientDataModel GetClientByData(string data);
+
+    void InsertClient(СlientDataModel clientDataModel);
+
+    void UpdateClient(СlientDataModel clientDataModel);
+
+    void DeleteClient(string id);
+}

AndDietCokeProject/AndDietCokeContracts/BusinessLogicsContracts/IDishBusinessLogicsContrats.cs

@@ -0,0 +1,21 @@
+using AndDietCokeContracts.DataModels;
+using System.Collections.Generic;
+
+namespace AndDietCokeContracts.BusinessLogicsContracts;
+
+public interface IDishBusinessLogicsContracts
+{
+    List<DishDataModel> GetAllDishes();
+
+    List<DishHistoryDataModel> GetDishHistory(string dishId);
+
+    DishDataModel? GetDishById(string id);
+
+    DishDataModel? GetDishByName(string name);
+
+    void InsertDish(DishDataModel dishDataModel);
+
+    void UpdateDish(DishDataModel dishDataModel);
+
+    void DeleteDish(string id);
+}

AndDietCokeProject/AndDietCokeContracts/BusinessLogicsContracts/IDish_OrderBusinessLogicsContrats.cs

@@ -0,0 +1,17 @@
+using AndDietCokeContracts.DataModels;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace AndDietCokeContracts.BusinessLogicsContracts;
+
+public interface IDish_OrderBusinessLogicsContracts
+{
+    List<Dish_OrderDataModel> GetAllDishOrders(string? orderId = null, string? dishId = null);
+    Dish_OrderDataModel? GetDishOrderById(string orderId, string dishId);
+    void InsertDishOrder(Dish_OrderDataModel dishOrderDataModel);
+    void UpdateDishOrder(Dish_OrderDataModel dishOrderDataModel);
+    void DeleteDishOrder(string orderId, string dishId);
+}

AndDietCokeProject/AndDietCokeContracts/BusinessLogicsContracts/IEmployeeBusinessLogicsContrats.cs

@@ -0,0 +1,19 @@
+using AndDietCokeContracts.DataModels;
+using System.Collections.Generic;
+
+namespace AndDietCokeContracts.BusinessLogicsContracts;
+
+public interface IEmployeeBusinessLogicsContracts
+{
+    List<EmployeeDataModel> GetAllEmployees(bool onlyActive = true, string? positionId = null, DateTime? fromBirthDate = null, DateTime? toBirthDate = null, DateTime? fromEmploymentDate = null, DateTime? toEmploymentDate = null);
+
+    EmployeeDataModel? GetEmployeeById(string id);
+
+    EmployeeDataModel? GetEmployeeByFIO(string fio);
+
+    void InsertEmployee(EmployeeDataModel employeeDataModel);
+
+    void UpdateEmployee(EmployeeDataModel employeeDataModel);
+
+    void DeleteEmployee(string id);
+}

AndDietCokeProject/AndDietCokeContracts/BusinessLogicsContracts/IOrderBusinessLogicsContrats.cs

@@ -0,0 +1,15 @@
+using AndDietCokeContracts.DataModels;
+using System.Collections.Generic;
+
+namespace AndDietCokeContracts.BusinessLogicsContracts;
+
+public interface IOrderBusinessLogicsContracts
+{
+    List<OrderDataModels> GetAllOrders(string? clientId = null, string? employeedId = null, string? dishId = null);
+
+    OrderDataModels? GetOrderById(string id);
+
+    void InsertOrder(OrderDataModels orderDataModel);
+
+    void DeleteOrder(string id);
+}

AndDietCokeProject/AndDietCokeContracts/BusinessLogicsContracts/IPositionBusinessLogicsContrats.cs

@@ -0,0 +1,15 @@
+using AndDietCokeContracts.DataModels;
+using System.Collections.Generic;
+
+namespace AndDietCokeContracts.BusinessLogicsContracts;
+
+public interface IPositionBusinessLogicsContracts
+{
+    List<PositionDataModel> GetAllPositions(bool onlyActive);
+    List<PositionDataModel> GetAllDataOfPosition(string positionId);
+    PositionDataModel GetPositionByData(string data);
+    void InsertPosition(PositionDataModel positionDataModel);
+    void UpdatePosition(PositionDataModel positionDataModel);
+    void DeletePosition(string id);
+    void RestorePosition(string id);
+}

AndDietCokeProject/AndDietCokeContracts/BusinessLogicsContracts/ISalaryBusinessLogicsContrats.cs

@@ -0,0 +1,13 @@
+using AndDietCokeContracts.DataModels;
+
+namespace AndDietCokeContracts.BusinessLogicsContracts
+{
+    public interface ISalaryBusinessLogicsContracts
+    {
+        List<SalaryDataModel> GetAllSalariesByPeriod(DateTime fromDate, DateTime toDate);
+
+        List<SalaryDataModel> GetAllSalariesByPeriodByEmployee(DateTime fromDate, DateTime toDate, string employeeId);
+
+        void CalculateSalaryByMonth(DateTime date);
+    }
+}

AndDietCokeProject/AndDietCokeContracts/DataModels/DishHistoryDataModel.cs

@@ -9,13 +9,12 @@ using System.Threading.Tasks;
 
 namespace AndDietCokeContracts.DataModels;
 
-public class DishHistoryDataModel(string productId, double oldPrice, string orderid) : IValidation
-
+public class DishHistoryDataModel(string dishId, double oldPrice, string orderId) : IValidation
 {
-    public string DishId { get; private set; } = productId;
+    public string DishId { get; private set; } = dishId;
     public double OldPrice { get; private set; } = oldPrice;
     public DateTime ChangeDate { get; private set; } = DateTime.UtcNow;
-    public string OrderId { get; private set; } = orderid;
+    public string OrderId { get; private set; } = orderId;
     public void Validate()
     {
         if (DishId.IsEmpty())

AndDietCokeProject/AndDietCokeContracts/DataModels/Dish_OrderDataModel.cs

@@ -1,39 +1,24 @@
-using AndDietCokeContracts.Enums;
-using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.Exceptions;
 using AndDietCokeContracts.Extensions;
-using System;
-using System.Collections.Generic;
-using System.Diagnostics;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using System.Xml.Linq;
 
 namespace AndDietCokeContracts.DataModels;
-public class Dish_OrderDataModel(string orderid, string dishid, int count)
+public class Dish_OrderDataModel(string orderId, string dishId, int count)
 {
-public string OrderId { get; private set; } = orderid;
-public string DishId { get; private set; } = dishid;
-public int Count { get; private set; } = count;
-
-
-
-
-
-public void Validate()
-{
-    
-
-    if (OrderId.IsEmpty())
-        throw new ValidationException("Field OrderId is empty");
-    if (!OrderId.IsGuid())
-        throw new ValidationException("The value in the field OrderId is not a unique identifier");
-    if (DishId.IsEmpty())
-        throw new ValidationException("Field DishId is empty");
-    if (!DishId.IsGuid())
-        throw new ValidationException("The value in the field DishId is not a unique identifier");
-    if (Count <= 0)
-        throw new ValidationException("Field Count is less than or equal to 0"); 
+    public string OrderId { get; private set; } = orderId;
+    public string DishId { get; private set; } = dishId;
+    public int Count { get; private set; } = count;
 
+    public void Validate()
+    {
+        if (OrderId.IsEmpty())
+            throw new ValidationException("Field OrderId is empty");
+        if (!OrderId.IsGuid())
+            throw new ValidationException("The value in the field OrderId is not a unique identifier");
+        if (DishId.IsEmpty())
+            throw new ValidationException("Field DishId is empty");
+        if (!DishId.IsGuid())
+            throw new ValidationException("The value in the field DishId is not a unique identifier");
+        if (Count <= 0)
+            throw new ValidationException("Field Count is less than or equal to 0"); 
     }
 }

AndDietCokeProject/AndDietCokeContracts/DataModels/OrderDataModels.cs

@@ -3,12 +3,12 @@ using AndDietCokeContracts.Extensions;
 using AndDietCokeContracts.Infrastructure;
 namespace AndDietCokeContracts.DataModels;
 
-public class OrderDataModels(string id, string clientid, string employeedid, List<Dish_OrderDataModel> dishes) : IValidation
+public class OrderDataModels(string id, string clientId, string employeeId, List<Dish_OrderDataModel> orderDishes) : IValidation
 {
 public string Id { get; private set; } = id;
-public string ClientId { get; private set; } = clientid;
-public string EmloyeedId { get; private set; } = employeedid;
-public List<Dish_OrderDataModel> Dishes { get; private set; } = dishes;
+public string ClientId { get; private set; } = clientId;
+public string EmloyeedId { get; private set; } = employeeId;
+public List<Dish_OrderDataModel> Dishes { get; private set; } = orderDishes;
     public void Validate()
 {
     if (Id.IsEmpty())

AndDietCokeProject/AndDietCokeContracts/DataModels/PositionDataModel.cs

@@ -2,14 +2,11 @@
 using AndDietCokeContracts.Exceptions;
 using AndDietCokeContracts.Extensions;
 using AndDietCokeContracts.Infrastructure;
-using System.Text.RegularExpressions;
-using System.Xml;
 namespace AndDietCokeContracts.DataModels;
 
-public class PositionDataModell(string id, string positionId, string positionName, PositionType positionType, double salary, bool isActual, DateTime changeDate) : IValidation
+public class PositionDataModel(string positionId, string positionName, PositionType positionType, double salary, bool isActual, DateTime changeDate) : IValidation
 {
-    public string Id { get; private set; } = id;
-    public string PositionId { get; private set; } = positionId;
+    public string Id { get; private set; } = positionId;
     public string PositionName { get; private set; } = positionName;
     public PositionType PositionType { get; private set; } = positionType;
     public double Salary { get; private set; } = salary;
@@ -21,10 +18,6 @@ public class PositionDataModell(string id, string positionId, string positionNam
             throw new ValidationException("Field Id is empty");
         if (!Id.IsGuid())
             throw new ValidationException("The value in the field Id is not a unique identifier");
-        if (PositionId.IsEmpty())
-            throw new ValidationException("Field PostId is empty");
-        if (!PositionId.IsGuid())
-            throw new ValidationException("The value in the field PostId is not a unique identifier");
         if (PositionName.IsEmpty())
             throw new ValidationException("Field PostName is empty");
         if (PositionType == PositionType.None)

AndDietCokeProject/AndDietCokeContracts/DataModels/SalaryDataModel.cs

@@ -4,12 +4,12 @@ using AndDietCokeContracts.Infrastructure;
 
 namespace AndDietCokeContracts.DataModels;
 
-public class SalaryDataModel(string id, DateTime salaryDate, double salary, string employeedid) : IValidation
+public class SalaryDataModel(string id, DateTime salaryDate, double salary, string emloyeedid) : IValidation
 {
     public string Id { get; private set; } = id;
     public DateTime SalaryDate { get; private set; } = salaryDate;
     public double Salary { get; private set; } = salary;
-    public string EmloyeedId { get; private set; } = employeedid;
+    public string EmloyeedId { get; private set; } = emloyeedid; 
 
     public void Validate()
     {

AndDietCokeProject/AndDietCokeContracts/Enums/DishType.cs

@@ -13,6 +13,8 @@ public enum DishType
     Pepperoni = 2,
     BBQChicken = 3,
     Veggie = 4,
-    Cola = 5
+    Cola = 5,
+    Soup = 6,
+    MainCourse = 7
 }
 

AndDietCokeProject/AndDietCokeContracts/Enums/PositionType.cs

@@ -12,5 +12,8 @@ public enum PositionType
     Waiter = 1,
     Сhef = 2,
     Manager = 3,
-    Assistant = 4
+    Assistant = 4,
+    Staff = 5,
+    Developer = 6,
+    QA = 7
 }

AndDietCokeProject/AndDietCokeContracts/Exceptions/DuplicateElementException.cs

@@ -0,0 +1,8 @@
+using AndDietCokeContracts.DataModels;
+
+public class DuplicateEmployeeException : Exception
+{
+    public DuplicateEmployeeException(string id)
+        : base($"Employee with ID {id} already exists") { }
+}
+

AndDietCokeProject/AndDietCokeContracts/Exceptions/ElementDeletedException.cs

@@ -0,0 +1,6 @@
+namespace AndDietCokeContracts.Exceptions;
+
+public class ElementDeletedException : Exception
+{
+    public ElementDeletedException(string id) : base($"Cannot modify a deleted item (id: {id})") { }
+}

AndDietCokeProject/AndDietCokeContracts/Exceptions/ElementExistsException.cs

@@ -0,0 +1,13 @@
+namespace AndDietCokeContracts.Exceptions;
+public class ElementExistsException : Exception
+{
+	public string ParamName { get; private set; }
+
+	public string ParamValue { get; private set; }
+
+	public ElementExistsException(string paramName, string paramValue) : base($"There is already an element with value{paramValue} of parameter {paramName}")
+	{
+		ParamName = paramName;
+		ParamValue = paramValue;
+	}
+}

AndDietCokeProject/AndDietCokeContracts/Exceptions/ElementNotFoundException.cs

@@ -0,0 +1,10 @@
+namespace AndDietCokeContracts.Exceptions;
+public class ElementNotFoundException : Exception
+{
+	public string Value { get; private set; }
+
+	public ElementNotFoundException(string value) : base($"Element not found at value = {value}")
+	{
+		Value = value;
+	}
+}

AndDietCokeProject/AndDietCokeContracts/Exceptions/IncorrectDatesException.cs

@@ -0,0 +1,5 @@
+namespace AndDietCokeContracts.Exceptions;
+public class IncorrectDatesException : Exception
+{
+	public IncorrectDatesException(DateTime start, DateTime end) : base($"The end date must be later than the start date.. StartDate: {start:dd.MM.YYYY}. EndDate: {end:dd.MM.YYYY}") { }
+}

AndDietCokeProject/AndDietCokeContracts/Exceptions/NullListException.cs

@@ -0,0 +1,6 @@
+namespace AndDietCokeContracts.Exceptions;
+
+public class NullListException : Exception
+{
+	public NullListException() : base("The returned list is null") { }
+}

AndDietCokeProject/AndDietCokeContracts/Exceptions/StorageException.cs

@@ -0,0 +1,5 @@
+namespace AndDietCokeContracts.Exceptions;
+public class StorageException : Exception
+{
+	public StorageException(Exception ex) : base($"Error while working in storage: {ex.Message}", ex) { }
+}

AndDietCokeProject/AndDietCokeContracts/Extensions/DateTimeExtensions.cs

@@ -0,0 +1,9 @@
+namespace AndDietCokeContracts.Extensions;
+
+public static class DateTimeExtensions
+{
+	public static bool IsDateNotOlder(this DateTime date, DateTime olderDate)
+	{
+		return date >= olderDate;
+	}
+}

AndDietCokeProject/AndDietCokeContracts/Infrastructure/IConfigurationDatabase.cs

@@ -0,0 +1,6 @@
+namespace AndDietCokeContracts.Infrastructure;
+
+public interface IConfigurationDatabase
+{
+    string ConnectionString { get; }
+}

AndDietCokeProject/AndDietCokeContracts/StoragesContracts/IClientStorageContract.cs

@@ -0,0 +1,20 @@
+using AndDietCokeContracts.DataModels;
+
+namespace AndDietCokeContracts.StoragesContracts;
+
+public interface IClientStorageContract
+{
+	List<СlientDataModel> GetList();
+
+    СlientDataModel? GetElementById(string id);
+
+    СlientDataModel? GetElementByPhoneNumber(string phoneNumber);
+
+    СlientDataModel? GetElementByFIO(string fio);
+
+	void AddElement(СlientDataModel clientDataModel);
+
+	void UpdElement(СlientDataModel clientDataModel);
+
+	void DelElement(string id);
+}

AndDietCokeProject/AndDietCokeContracts/StoragesContracts/IDishStorageContracts.cs

@@ -0,0 +1,25 @@
+using AndDietCokeContracts.DataModels;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace AndDietCokeContracts.StoragesContracts;
+
+public interface IDishStorageContracts
+{
+    List<DishDataModel> GetList();
+
+    List<DishHistoryDataModel> GetHistoryByProductId(string dishId);
+
+    DishDataModel? GetElementById(string id);
+
+    DishDataModel? GetElementByName(string name);
+
+    void AddElement(DishDataModel dishDataModel);
+
+    void UpdElement(DishDataModel dishDataModel);
+
+    void DelElement(string id);
+}

AndDietCokeProject/AndDietCokeContracts/StoragesContracts/IDish_OrderStorageContract.cs

@@ -0,0 +1,22 @@
+using AndDietCokeContracts.DataModels;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace AndDietCokeContracts.StoragesContracts;
+
+public interface IDish_OrderStorageContract
+{
+    List<Dish_OrderDataModel> GetList(string? orderId = null, string? dishId = null);
+
+    Dish_OrderDataModel? GetElementById(string orderId, string dishId);
+
+    void AddElement(Dish_OrderDataModel dishOrderDataModel);
+
+    void UpdElement(Dish_OrderDataModel dishOrderDataModel);
+
+    void DelElement(string orderId, string dishId);
+}
+

AndDietCokeProject/AndDietCokeContracts/StoragesContracts/IEmployeeStoragesContracts.cs

@@ -0,0 +1,16 @@
+using AndDietCokeContracts.DataModels;
+namespace AndDietCokeContracts.StoragesContracts;
+public interface IEmployeeStoragesContracts
+{
+    List<EmployeeDataModel> GetList(bool onlyActive = true, string? positionId = null, DateTime? fromBirthDate = null, DateTime? toBirthDate = null, DateTime? fromEmploymentDate = null, DateTime? toEmploymentDate = null);
+
+    EmployeeDataModel? GetElementById(string id);
+
+    EmployeeDataModel? GetElementByFIO(string fio);
+
+    void AddElement(EmployeeDataModel employeeDataModel);
+
+    void UpdElement(EmployeeDataModel employeeDataModel);
+
+    void DelElement(string id);
+}

AndDietCokeProject/AndDietCokeContracts/StoragesContracts/IOrderStorageContracts.cs

@@ -0,0 +1,14 @@
+using AndDietCokeContracts.DataModels;
+
+namespace AndDietCokeContracts.StorageContracts;
+
+public interface IOrderStorageContracts
+{
+    List<OrderDataModels> GetList(string? clientId = null, string? employeedId = null, string? dishId = null);
+
+    OrderDataModels? GetElementById(string id);
+
+    void AddElement(OrderDataModels orderDataModel);
+
+    void DelElement(string id);
+}

AndDietCokeProject/AndDietCokeContracts/StoragesContracts/IPositionStorageContract.cs

@@ -0,0 +1,19 @@
+using AndDietCokeContracts.DataModels;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace AndDietCokeContracts.StoragesContracts;
+public interface IPositionStorageContract
+{
+    List<PositionDataModel> GetList(bool onlyActual = true);
+    List<PositionDataModel> GetPostWithHistory(string postId);
+    PositionDataModel? GetElementById(string id);
+    PositionDataModel? GetElementByName(string name);
+    void AddElement(PositionDataModel positionDataModell);
+    void UpdElement(PositionDataModel positionDataModell);
+    void DelElement(string id);
+    void ResElement(string id);
+}

AndDietCokeProject/AndDietCokeContracts/StoragesContracts/ISalaryStorageContract.cs

@@ -0,0 +1,11 @@
+using AndDietCokeContracts.DataModels;
+
+namespace AndDietCokeContracts.StorageContract
+{
+    public interface ISalaryStorageContract
+    {
+        List<SalaryDataModel> GetList(DateTime startDate, DateTime endDate, string? employeeId = null);
+
+        void AddElement(SalaryDataModel salaryDataModel);
+    }
+}

AndDietCokeProject/AndDietCokeDatabase/AndDietCokeDatabase.csproj

@@ -0,0 +1,19 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="AutoMapper" Version="14.0.0" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="9.0.2" />
+    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="9.0.4" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\AndDietCokeBusinessLogic\AndDietCokeBusinessLogic.csproj" />
+  </ItemGroup>
+
+</Project>

AndDietCokeProject/AndDietCokeDatabase/AndDietCokeDbContext.cs

@@ -0,0 +1,54 @@
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Infrastructure;
+using AndDietCokeDatabase.Models;
+using Microsoft.EntityFrameworkCore;
+namespace AndDietCokeDatabase;
+
+public class AndDietCokeDbContext(IConfigurationDatabase configurationDatabase) : DbContext
+{
+    private readonly IConfigurationDatabase? _configurationDatabase = configurationDatabase;
+
+    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
+    {
+        optionsBuilder.UseNpgsql(_configurationDatabase?.ConnectionString, o => o.SetPostgresVersion(12, 2));
+        base.OnConfiguring(optionsBuilder);
+    }
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        base.OnModelCreating(modelBuilder);
+
+        modelBuilder.Entity<Client>().HasIndex(x => x.Contact).IsUnique();
+
+        modelBuilder.Entity<Dish>().HasIndex(x => x.Name).IsUnique();
+
+        modelBuilder.Entity<Position>()
+            .HasIndex(e => new { e.PositionName, e.IsActual })
+            .IsUnique()
+            .HasFilter($"\"{nameof(Position.IsActual)}\" = TRUE");
+
+        modelBuilder.Entity<Position>()
+            .HasIndex(e => new { e.PositionId, e.IsActual })
+            .IsUnique()
+            .HasFilter($"\"{nameof(Position.IsActual)}\" = TRUE");
+
+        modelBuilder.Entity<Dish_Order>().HasKey(x => new { x.DishId, x.OrderId });
+
+    }
+
+    public DbSet<Client> Clients { get; set; }
+
+    public DbSet<Position> Posts { get; set; }
+
+    public DbSet<Dish> Dishes { get; set; }
+
+    public DbSet<DishHistory> DishHistories { get; set; }
+
+    public DbSet<Salaries> Salaries { get; set; }
+
+    public DbSet<Order> Orders { get; set; }
+
+    public DbSet<Dish_Order> Dish_Orders { get; set; }
+
+    public DbSet<Employee> Employees { get; set; }
+}

AndDietCokeProject/AndDietCokeDatabase/Implementations/ClientStorageContract.cs

@@ -0,0 +1,149 @@
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.StoragesContracts;
+using AndDietCokeDatabase.Models;
+using AutoMapper;
+using Microsoft.EntityFrameworkCore;
+using Npgsql;
+
+namespace AndDietCokeDatabase.Implementations;
+
+public class ClientStorageContract : IClientStorageContract
+{
+    private readonly AndDietCokeDbContext _dbContext;
+    private readonly Mapper _mapper;
+
+    public ClientStorageContract(AndDietCokeDbContext dbContext)
+    {
+        _dbContext = dbContext;
+        var config = new MapperConfiguration(cfg =>
+        {
+            cfg.AddMaps(typeof(Client));
+        });
+        _mapper = new Mapper(config);
+    }
+
+    public List<СlientDataModel> GetList()
+    {
+        try
+        {
+            return [.. _dbContext.Clients.Select(x => _mapper.Map<СlientDataModel>(x))];
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public СlientDataModel? GetElementById(string id)
+    {
+        try
+        {
+            return _mapper.Map<СlientDataModel>(GetClientById(id));
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public СlientDataModel? GetElementByFIO(string fio)
+    {
+        try
+        {
+            return _mapper.Map<СlientDataModel>(_dbContext.Clients.FirstOrDefault(x => x.FIO == fio));
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public СlientDataModel? GetElementByPhoneNumber(string phoneNumber)
+    {
+        try
+        {
+            return _mapper.Map<СlientDataModel>(_dbContext.Clients.FirstOrDefault(x => x.Contact == phoneNumber));
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public void AddElement(СlientDataModel clientDataModel)
+    {
+
+        try
+        {
+            _dbContext.Clients.Add(_mapper.Map<Client>(clientDataModel));
+            _dbContext.SaveChanges();
+        }
+        catch (InvalidOperationException ex) when (ex.TargetSite?.Name == "ThrowIdentityConflict")
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new ElementExistsException("Id", clientDataModel.Id);
+        }
+        catch (DbUpdateException ex) when (ex.InnerException is PostgresException { ConstraintName: "IX_Clients_Contact" })
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new ElementExistsException("Contact", clientDataModel.Contact);
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public void UpdElement(СlientDataModel clientDataModel)
+    {
+        try
+        {
+            var element = GetClientById(clientDataModel.Id) ?? throw new ElementNotFoundException(clientDataModel.Id);
+            _dbContext.Clients.Update(_mapper.Map(clientDataModel, element));
+            _dbContext.SaveChanges();
+        }
+        catch (ElementNotFoundException)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw;
+        }
+        catch (DbUpdateException ex) when (ex.InnerException is PostgresException { ConstraintName: "IX_Clients_Contact" })
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new ElementExistsException("Contact", clientDataModel.Contact);
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public void DelElement(string id)
+    {
+        try
+        {
+            var element = GetClientById(id) ?? throw new ElementNotFoundException(id);
+            _dbContext.Clients.Remove(element);
+            _dbContext.SaveChanges();
+        }
+        catch (ElementNotFoundException)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw;
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    private Client? GetClientById(string id) => _dbContext.Clients.FirstOrDefault(x => x.Id == id);
+}

AndDietCokeProject/AndDietCokeDatabase/Implementations/DishStorageContract.cs

@@ -0,0 +1,166 @@
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.StoragesContracts;
+using AndDietCokeDatabase.Models;
+using AutoMapper;
+using Microsoft.EntityFrameworkCore;
+using Npgsql;
+
+namespace AndDietCokeDatabase.Implementations;
+
+public class DishStorageContract : IDishStorageContracts
+{
+
+    private readonly AndDietCokeDbContext _dbContext;
+    private readonly Mapper _mapper;
+
+    public DishStorageContract(AndDietCokeDbContext dbContext)
+    {
+        _dbContext = dbContext;
+        var config = new MapperConfiguration(cfg =>
+        {
+            cfg.AddMaps(typeof(Dish));
+            cfg.AddMaps(typeof(DishHistory));
+        });
+        _mapper = new Mapper(config);
+    }
+
+    public List<DishDataModel> GetList()
+    {
+        try
+        {
+            var query = _dbContext.Dishes.AsQueryable();
+            return [.. query.Select(x => _mapper.Map<DishDataModel>(x))];
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public List<DishHistoryDataModel> GetHistoryByProductId(string productId)
+    {
+        try
+        {
+            return [.. _dbContext.DishHistories.Where(x => x.DishId == productId).OrderByDescending(x => x.ChangeDate).Select(x => _mapper.Map<DishHistoryDataModel>(x))];
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public DishDataModel? GetElementById(string id)
+    {
+        try
+        {
+            return _mapper.Map<DishDataModel>(GetDishById(id));
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public DishDataModel? GetElementByName(string name)
+    {
+        try
+        {
+            return _mapper.Map<DishDataModel>(_dbContext.Dishes.FirstOrDefault(x => x.Name == name));
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public void AddElement(DishDataModel DishDataModel)
+    {
+        try
+        {
+            _dbContext.Dishes.Add(_mapper.Map<Dish>(DishDataModel));
+            _dbContext.SaveChanges();
+        }
+        catch (InvalidOperationException ex) when (ex.TargetSite?.Name == "ThrowIdentityConflict")
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new ElementExistsException("Id", DishDataModel.Id);
+        }
+        catch (DbUpdateException ex) when (ex.InnerException is PostgresException { ConstraintName: "IX_Dishes_Name" })
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new ElementExistsException("Name", DishDataModel.Name);
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public void UpdElement(DishDataModel DishDataModel)
+    {
+        try
+        {
+            var transaction = _dbContext.Database.BeginTransaction();
+            try
+            {
+                var element = GetDishById(DishDataModel.Id) ?? throw new ElementNotFoundException(DishDataModel.Id);
+                if (element.Price != DishDataModel.Price)
+                {
+                    _dbContext.DishHistories.Add(new DishHistory() { DishId = element.Id, OldPrice = element.Price, OrderId = element.OrderId });
+                    _dbContext.SaveChanges();
+                }
+                _dbContext.Dishes.Update(_mapper.Map(DishDataModel, element));
+                _dbContext.SaveChanges();
+                transaction.Commit();
+            }
+            catch
+            {
+                transaction.Rollback();
+                throw;
+            }
+        }
+        catch (DbUpdateException ex) when (ex.InnerException is PostgresException { ConstraintName: "IX_Dishes_Name" })
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new ElementExistsException("Name", DishDataModel.Name);
+        }
+        catch (Exception ex) when (ex is ElementDeletedException || ex is ElementNotFoundException)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw;
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public void DelElement(string id)
+    {
+        try
+        {
+            var element = GetDishById(id) ?? throw new ElementNotFoundException(id);
+            _dbContext.Dishes.Remove(element);
+            _dbContext.SaveChanges();
+        }
+        catch (ElementNotFoundException ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw;
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    private Dish? GetDishById(string id) => _dbContext.Dishes.FirstOrDefault(x => x.Id == id);
+}

AndDietCokeProject/AndDietCokeDatabase/Implementations/EmployeeStorageContract.cs

@@ -0,0 +1,140 @@
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.StoragesContracts;
+using AndDietCokeDatabase.Models;
+using AutoMapper;
+
+namespace AndDietCokeDatabase.Implementations;
+
+public class EmployeeStorageContract : IEmployeeStoragesContracts
+{
+    private readonly AndDietCokeDbContext _dbContext;
+    private readonly Mapper _mapper;
+
+    public EmployeeStorageContract(AndDietCokeDbContext dbContext)
+    {
+        _dbContext = dbContext;
+        var config = new MapperConfiguration(cfg =>
+        {
+            cfg.AddMaps(typeof(Employee));
+        });
+        _mapper = new Mapper(config);
+    }
+
+    public List<EmployeeDataModel> GetList(bool onlyActive = true, string? postId = null, DateTime? fromBirthDate = null, DateTime? toBirthDate = null, DateTime? fromEmploymentDate = null, DateTime? toEmploymentDate = null)
+    {
+        try
+        {
+            var query = _dbContext.Employees.AsQueryable();
+            if (onlyActive)
+            {
+                query = query.Where(x => !x.IsDeleted);
+            }
+            if (postId is not null)
+            {
+                query = query.Where(x => x.PositionId == postId);
+            }
+            if (fromBirthDate is not null && toBirthDate is not null)
+            {
+                query = query.Where(x => x.BirthDate >= fromBirthDate && x.BirthDate <= toBirthDate);
+            }
+            if (fromEmploymentDate is not null && toEmploymentDate is not null)
+            {
+                query = query.Where(x => x.EmploymentDate >= fromEmploymentDate && x.EmploymentDate <= toEmploymentDate);
+            }
+            return [.. query.Select(x => _mapper.Map<EmployeeDataModel>(x))];
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public EmployeeDataModel? GetElementById(string id)
+    {
+        try
+        {
+            return _mapper.Map<EmployeeDataModel>(GetEmployeeById(id));
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public EmployeeDataModel? GetElementByFIO(string fio)
+    {
+        try
+        {
+            return _mapper.Map<EmployeeDataModel>(_dbContext.Employees.FirstOrDefault(x => x.FIO == fio));
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public void AddElement(EmployeeDataModel EmployeeDataModel)
+    {
+        try
+        {
+            _dbContext.Employees.Add(_mapper.Map<Employee>(EmployeeDataModel));
+            _dbContext.SaveChanges();
+        }
+        catch (InvalidOperationException ex) when (ex.TargetSite?.Name == "ThrowIdentityConflict")
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new ElementExistsException("Id", EmployeeDataModel.Id);
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public void UpdElement(EmployeeDataModel EmployeeDataModel)
+    {
+        try
+        {
+            var element = GetEmployeeById(EmployeeDataModel.Id) ?? throw new ElementNotFoundException(EmployeeDataModel.Id);
+            _dbContext.Employees.Update(_mapper.Map(EmployeeDataModel, element));
+            _dbContext.SaveChanges();
+        }
+        catch (ElementNotFoundException)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw;
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public void DelElement(string id)
+    {
+        try
+        {
+            var element = GetEmployeeById(id) ?? throw new ElementNotFoundException(id);
+            element.IsDeleted = true;
+            _dbContext.SaveChanges();
+        }
+        catch (ElementNotFoundException)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw;
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    private Employee? GetEmployeeById(string id) => _dbContext.Employees.FirstOrDefault(x => x.Id == id && !x.IsDeleted);
+}

AndDietCokeProject/AndDietCokeDatabase/Implementations/OrderStorageContract.cs

@@ -0,0 +1,103 @@
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.StorageContracts;
+using AndDietCokeDatabase.Models;
+using AutoMapper;
+using Microsoft.EntityFrameworkCore;
+
+namespace AndDietCokeDatabase.Implementations;
+
+public class OrderStorageContract : IOrderStorageContracts
+{
+    private readonly AndDietCokeDbContext _dbContext;
+    private readonly Mapper _mapper;
+
+    public OrderStorageContract(AndDietCokeDbContext dbContext)
+    {
+        _dbContext = dbContext;
+        var config = new MapperConfiguration(cfg =>
+        {
+            cfg.CreateMap<Dish_Order, Dish_OrderDataModel>();
+            cfg.CreateMap<Dish_OrderDataModel, Dish_Order>();
+            cfg.CreateMap<Order, OrderDataModels>();
+            cfg.CreateMap<OrderDataModels, Order>()
+                .ForMember(x => x.OrderDishes, x => x.MapFrom(src => src.Dishes));
+        });
+        _mapper = new Mapper(config);
+    }
+
+    public List<OrderDataModels> GetList(string? clientId = null, string? employeedId = null, string? dishId = null)
+    {
+        try
+        {
+            var query = _dbContext.Orders.Include(x => x.OrderDishes).AsQueryable();
+            if (employeedId is not null)
+            {
+                query = query.Where(x => x.EmloyeedId == employeedId);
+            }
+            if (clientId is not null)
+            {
+                query = query.Where(x => x.ClientId == clientId);
+            }
+            if (dishId is not null)
+            {
+                query = query.Where(x => x.OrderDishes!.Any(y => y.DishId == dishId));
+            }
+            return [.. query.Select(x => _mapper.Map<OrderDataModels>(x))];
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public OrderDataModels? GetElementById(string id)
+    {
+        try
+        {
+            return _mapper.Map<OrderDataModels>(GetOrderById(id));
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public void AddElement(OrderDataModels orderDataModel)
+    {
+        try
+        {
+            _dbContext.Orders.Add(_mapper.Map<Order>(orderDataModel));
+            _dbContext.SaveChanges();
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public void DelElement(string id)
+    {
+        try
+        {
+            var element = GetOrderById(id) ?? throw new ElementNotFoundException(id);
+            _dbContext.Remove(element);
+            _dbContext.SaveChanges();
+        }
+        catch (Exception ex) when (ex is ElementDeletedException || ex is ElementNotFoundException)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw;
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    private Order? GetOrderById(string id) => _dbContext.Orders.FirstOrDefault(x => x.Id == id);
+}

AndDietCokeProject/AndDietCokeDatabase/Implementations/PositionStorageContract.cs

@@ -0,0 +1,190 @@
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.StoragesContracts;
+using AndDietCokeDatabase.Models;
+using AutoMapper;
+using Microsoft.EntityFrameworkCore;
+using Npgsql;
+
+namespace AndDietCokeDatabase.Implementations;
+
+public class PositionStorageContract : IPositionStorageContract
+{
+    private readonly AndDietCokeDbContext _dbContext;
+    private readonly Mapper _mapper;
+
+    public PositionStorageContract(AndDietCokeDbContext dbContext)
+    {
+        _dbContext = dbContext;
+        var config = new MapperConfiguration(cfg =>
+        {
+            cfg.CreateMap<Position, PositionDataModel>()
+                .ForMember(x => x.Id, x => x.MapFrom(src => src.PositionId));
+            cfg.CreateMap<PositionDataModel, Position>()
+                .ForMember(x => x.Id, x => x.Ignore())
+                .ForMember(x => x.PositionId, x => x.MapFrom(src => src.Id))
+                .ForMember(x => x.IsActual, x => x.MapFrom(src => true))
+                .ForMember(x => x.ChangeDate, x => x.MapFrom(src => DateTime.UtcNow));
+        });
+        _mapper = new Mapper(config);
+    }
+
+    public List<PositionDataModel> GetList(bool onlyActual = true)
+    {
+        try
+        {
+            var query = _dbContext.Posts.AsQueryable();
+            if (onlyActual)
+            {
+                query = query.Where(x => x.IsActual);
+            }
+            return [.. query.Select(x => _mapper.Map<PositionDataModel>(x))];
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public PositionDataModel? GetElementById(string id)
+    {
+        try
+        {
+            return _mapper.Map<PositionDataModel>(_dbContext.Posts.FirstOrDefault(x => x.PositionId == id && x.IsActual));
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public PositionDataModel? GetElementByName(string name)
+    {
+        try
+        {
+            return _mapper.Map<PositionDataModel>(_dbContext.Posts.FirstOrDefault(x => x.PositionName == name && x.IsActual));
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public List<PositionDataModel> GetPostWithHistory(string postId)
+    {
+        try
+        {
+            return [.. _dbContext.Posts.Where(x => x.PositionId == postId).Select(x => _mapper.Map<PositionDataModel>(x))];
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public void AddElement(PositionDataModel positionDataModell)
+    {
+        try
+        {
+            _dbContext.Posts.Add(_mapper.Map<Position>(positionDataModell));
+            _dbContext.SaveChanges();
+        }
+        catch (DbUpdateException ex) when (ex.InnerException is PostgresException { ConstraintName: "IX_Posts_PositionName_IsActual" })
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new ElementExistsException("PositionName", positionDataModell.PositionName);
+        }
+        catch (DbUpdateException ex) when (ex.InnerException is PostgresException { ConstraintName: "IX_Posts_PositionId_IsActual" })
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new ElementExistsException("PositionId", positionDataModell.Id);
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public void UpdElement(PositionDataModel positionDataModell)
+    {
+        try
+        {
+            var transaction = _dbContext.Database.BeginTransaction();
+            try
+            {
+                var element = GetPostById(positionDataModell.Id) ?? throw new ElementNotFoundException(positionDataModell.Id);
+                if (!element.IsActual)
+                {
+                    throw new ElementDeletedException(positionDataModell.Id);
+                }
+                element.IsActual = false;
+                _dbContext.SaveChanges();
+                var newElement = _mapper.Map<Position>(positionDataModell);
+                _dbContext.Posts.Add(newElement);
+                _dbContext.SaveChanges();
+                transaction.Commit();
+            }
+            catch
+            {
+                transaction.Rollback();
+                throw;
+            }
+        }
+        catch (DbUpdateException ex) when (ex.InnerException is PostgresException { ConstraintName: "IX_Posts_PositionName_IsActual" })
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new ElementExistsException("PositionName", positionDataModell.PositionName);
+        }
+        catch (Exception ex) when (ex is ElementDeletedException || ex is ElementNotFoundException)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw;
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public void DelElement(string id)
+    {
+        try
+        {
+            var element = GetPostById(id) ?? throw new ElementNotFoundException(id);
+            if (!element.IsActual)
+            {
+                throw new ElementDeletedException(id);
+            }
+            element.IsActual = false;
+            _dbContext.SaveChanges();
+        }
+        catch
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw;
+        }
+    }
+
+    public void ResElement(string id)
+    {
+        try
+        {
+            var element = GetPostById(id) ?? throw new ElementNotFoundException(id);
+            element.IsActual = true;
+            _dbContext.SaveChanges();
+        }
+        catch
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw;
+        }
+    }
+
+    private Position? GetPostById(string id) => _dbContext.Posts.Where(x => x.PositionId == id).OrderByDescending(x => x.ChangeDate).FirstOrDefault();
+}

AndDietCokeProject/AndDietCokeDatabase/Implementations/SalaryStorageContract.cs

@@ -0,0 +1,57 @@
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.StorageContract;
+using AndDietCokeDatabase.Models;
+using AutoMapper;
+
+namespace AndDietCokeDatabase.Implementations;
+
+public class SalaryStorageContract : ISalaryStorageContract
+{
+    private readonly AndDietCokeDbContext _dbContext;
+    private readonly Mapper _mapper;
+
+    public SalaryStorageContract(AndDietCokeDbContext dbContext)
+    {
+        _dbContext = dbContext;
+        var config = new MapperConfiguration(cfg =>
+        {
+            cfg.CreateMap<Salaries, SalaryDataModel>();
+            cfg.CreateMap<SalaryDataModel, Salaries>()
+                .ForMember(dest => dest.Salary, opt => opt.MapFrom(src => src.Salary));
+        });
+        _mapper = new Mapper(config);
+    }
+
+    public List<SalaryDataModel> GetList(DateTime startDate, DateTime endDate, string? workerId = null)
+    {
+        try
+        {
+            var query = _dbContext.Salaries.Where(x => x.SalaryDate >= startDate && x.SalaryDate <= endDate);
+            if (workerId is not null)
+            {
+                query = query.Where(x => x.EmloyeedId == workerId);
+            }
+            return [.. query.Select(x => _mapper.Map<SalaryDataModel>(x))];
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+
+    public void AddElement(SalaryDataModel salaryDataModel)
+    {
+        try
+        {
+            _dbContext.Salaries.Add(_mapper.Map<Salaries>(salaryDataModel));
+            _dbContext.SaveChanges();
+        }
+        catch (Exception ex)
+        {
+            _dbContext.ChangeTracker.Clear();
+            throw new StorageException(ex);
+        }
+    }
+}

AndDietCokeProject/AndDietCokeDatabase/Models/Client.cs

@@ -0,0 +1,17 @@
+using AndDietCokeContracts.DataModels;
+using AutoMapper;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace AndDietCokeDatabase.Models;
+
+[AutoMap(typeof(СlientDataModel), ReverseMap = true)]
+public class Client
+{
+    public required string Id { get; set; }
+    public required string FIO { get; set; }
+    public required string Contact { get; set; }
+    public double DiscountSize { get; set; }
+
+    [ForeignKey("ClientId")]
+    public List<Order>? Orders { get; set; }
+}

AndDietCokeProject/AndDietCokeDatabase/Models/Dish.cs

@@ -0,0 +1,22 @@
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Enums;
+using AutoMapper;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace AndDietCokeDatabase.Models;
+
+[AutoMap(typeof(DishDataModel), ReverseMap = true)]
+public class Dish
+{
+    public required string Id { get; set; }
+    public required string Name { get; set; }
+    public DishType DishType { get; set; }
+    public double Price { get; set; }
+    public required string OrderId { get; set; }
+
+    [ForeignKey("DishId")]
+    public List<Dish_Order>? DishOrders { get; set; }
+
+    [ForeignKey("DishId")]
+    public List<DishHistory>? DishHistories { get; set; }
+}

AndDietCokeProject/AndDietCokeDatabase/Models/DishHistory.cs

@@ -0,0 +1,15 @@
+using AndDietCokeContracts.DataModels;
+using AutoMapper;
+
+namespace AndDietCokeDatabase.Models;
+
+[AutoMap(typeof(DishHistoryDataModel), ReverseMap = true)]
+public class DishHistory
+{
+    public string Id { get; set; } = Guid.NewGuid().ToString();
+    public required string DishId { get; set; } 
+    public double OldPrice { get; set; }
+    public DateTime ChangeDate { get; set; } = DateTime.UtcNow;
+    public required string OrderId { get; set; }
+    public Dish? Dish { get; set; }
+}

AndDietCokeProject/AndDietCokeDatabase/Models/Dish_Order.cs

@@ -0,0 +1,10 @@
+namespace AndDietCokeDatabase.Models;
+
+public class Dish_Order
+{
+    public required string OrderId { get; set; }
+    public required string DishId { get; set; }
+    public int Count { get; set; }
+    public Order? Order { get; set; }
+    public Dish? Dish { get; set; }
+}

AndDietCokeProject/AndDietCokeDatabase/Models/Employee.cs

@@ -0,0 +1,24 @@
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Enums;
+using AutoMapper;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace AndDietCokeDatabase.Models;
+
+[AutoMap(typeof(EmployeeDataModel), ReverseMap = true)]
+public class Employee
+{
+    public required string Id { get; set; }
+    public required string FIO { get; set; }
+    public required string PositionId { get; set; }
+    public PositionType PositionType { get; set; }
+    public DateTime BirthDate { get; set; }
+    public DateTime EmploymentDate { get; set; }
+    public bool IsDeleted { get; set; }
+
+    [ForeignKey("EmployeeId")]
+    public List<Order>? Orders { get; set; }
+
+    [ForeignKey("EmployeeId")]
+    public List<Salaries>? Salaries { get; set; }
+}

AndDietCokeProject/AndDietCokeDatabase/Models/Order.cs

@@ -0,0 +1,15 @@
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace AndDietCokeDatabase.Models;
+
+public class Order
+{
+    public string Id { get; set; } = Guid.NewGuid().ToString();
+    public string? ClientId { get; set; }
+    public required string EmloyeedId { get; set; }
+    public Employee? Employee { get; set; }
+    public Client? Client { get; set; }
+
+    [ForeignKey("OrderId")]
+    public List<Dish_Order>? OrderDishes { get; set; }
+}

AndDietCokeProject/AndDietCokeDatabase/Models/Position.cs

@@ -0,0 +1,14 @@
+using AndDietCokeContracts.Enums;
+
+namespace AndDietCokeDatabase.Models;
+
+public class Position
+{
+    public string Id { get; set; } = Guid.NewGuid().ToString();
+    public required string PositionId { get; set; }
+    public required string PositionName { get; set; }
+    public PositionType PositionType { get; set; }
+    public double Salary { get; set; }
+    public bool IsActual { get; set; }
+    public DateTime ChangeDate { get; set; }
+}

AndDietCokeProject/AndDietCokeDatabase/Models/Salaries.cs

@@ -0,0 +1,10 @@
+namespace AndDietCokeDatabase.Models;
+
+public class Salaries
+{
+    public string Id { get; set; } = Guid.NewGuid().ToString();
+    public DateTime SalaryDate { get; set; }
+    public double Salary { get; set; }
+    public required string EmloyeedId { get; set; }
+    public Employee? Employee { get; set; }
+}

AndDietCokeProject/AndDietCokeProject.sln

@@ -7,6 +7,10 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AndDietCokeContracts", "And
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AndDietCokeTests", "AndDietCokeTests\AndDietCokeTests.csproj", "{97CF49C2-6F17-4FCB-B2AD-D84AED6A1AF9}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AndDietCokeBusinessLogic", "AndDietCokeBusinessLogic\AndDietCokeBusinessLogic.csproj", "{950B374D-94CC-4EE2-BD25-E78D5CDA5F2F}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AndDietCokeDatabase", "AndDietCokeDatabase\AndDietCokeDatabase.csproj", "{C303A979-1D68-4503-7DFA-928014D2D78A}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -21,8 +25,19 @@ Global
 		{97CF49C2-6F17-4FCB-B2AD-D84AED6A1AF9}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{97CF49C2-6F17-4FCB-B2AD-D84AED6A1AF9}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{97CF49C2-6F17-4FCB-B2AD-D84AED6A1AF9}.Release|Any CPU.Build.0 = Release|Any CPU
+		{950B374D-94CC-4EE2-BD25-E78D5CDA5F2F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{950B374D-94CC-4EE2-BD25-E78D5CDA5F2F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{950B374D-94CC-4EE2-BD25-E78D5CDA5F2F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{950B374D-94CC-4EE2-BD25-E78D5CDA5F2F}.Release|Any CPU.Build.0 = Release|Any CPU
+		{C303A979-1D68-4503-7DFA-928014D2D78A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{C303A979-1D68-4503-7DFA-928014D2D78A}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{C303A979-1D68-4503-7DFA-928014D2D78A}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{C303A979-1D68-4503-7DFA-928014D2D78A}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
 	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {6545237B-96EA-4C80-963A-F4CB39480436}
+	EndGlobalSection
 EndGlobal

AndDietCokeProject/AndDietCokeTests/AndDietCokeTests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFramework>net8.0</TargetFramework>
@@ -11,14 +11,18 @@
 
   <ItemGroup>
     <PackageReference Include="coverlet.collector" Version="6.0.0" />
+    <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="9.0.4" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
+    <PackageReference Include="Moq" Version="4.20.72" />
     <PackageReference Include="NUnit" Version="3.14.0" />
     <PackageReference Include="NUnit.Analyzers" Version="3.9.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="4.5.0" />
   </ItemGroup>
 
   <ItemGroup>
+    <ProjectReference Include="..\AndDietCokeBusinessLogic\AndDietCokeBusinessLogic.csproj" />
     <ProjectReference Include="..\AndDietCokeContracts\AndDietCokeContracts.csproj" />
+    <ProjectReference Include="..\AndDietCokeDatabase\AndDietCokeDatabase.csproj" />
   </ItemGroup>
 
   <ItemGroup>

AndDietCokeProject/AndDietCokeTests/BusinessLogicsContractsTests/DishBusinessLogicContractTests.cs

@@ -0,0 +1,228 @@
+using AndDietCokeBusinessLogic.Implementations;
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Enums;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.StoragesContracts;
+using Microsoft.Extensions.Logging;
+using Moq;
+
+namespace AndDietCokeTests.BusinessLogicsContractsTests
+{
+    [TestFixture]
+    internal class DishBusinessLogicContractTests
+    {
+        private DishBusinessLogicContract _dishBusinessLogic;
+        private Mock<IDishStorageContracts> _dishStorageMock;
+        private Mock<ILogger<DishBusinessLogicContract>> _loggerMock;
+
+        [OneTimeSetUp]
+        public void OneTimeSetUp()
+        {
+            _dishStorageMock = new Mock<IDishStorageContracts>();
+            _loggerMock = new Mock<ILogger<DishBusinessLogicContract>>();
+            _dishBusinessLogic = new DishBusinessLogicContract(
+                _dishStorageMock.Object, 
+                _loggerMock.Object);
+        }
+
+        [SetUp]
+        public void SetUp()
+        {
+            _dishStorageMock.Reset();
+            _loggerMock.Reset();
+        }
+
+        [Test]
+        public void GetAllDishes_ReturnListOfRecords_Test()
+        {
+            // Arrange
+            var testDishes = new List<DishDataModel>
+            {
+                new(Guid.NewGuid().ToString(), "Борщ", DishType.Soup, 250.50, Guid.NewGuid().ToString()),
+                new(Guid.NewGuid().ToString(), "Стейк", DishType.MainCourse, 1200.00, Guid.NewGuid().ToString())
+            };
+
+            _dishStorageMock.Setup(x => x.GetList()).Returns(testDishes);
+
+            // Act
+            var result = _dishBusinessLogic.GetAllDishes();
+
+            // Assert
+            Assert.Multiple(() =>
+            {
+                Assert.That(result, Is.Not.Null);
+                Assert.That(result, Is.EquivalentTo(testDishes));
+            });
+            _dishStorageMock.Verify(x => x.GetList(), Times.Once);
+        }
+
+        [Test]
+        public void GetAllDishes_ReturnEmptyList_Test()
+        {
+            // Arrange
+            _dishStorageMock.Setup(x => x.GetList()).Returns(new List<DishDataModel>());
+
+            // Act
+            var result = _dishBusinessLogic.GetAllDishes();
+
+            // Assert
+            Assert.Multiple(() =>
+            {
+                Assert.That(result, Is.Not.Null);
+                Assert.That(result, Has.Count.EqualTo(0));
+            });
+        }
+
+        [Test]
+        public void GetAllDishes_ReturnNull_ThrowException_Test()
+        {
+            // Arrange
+            _dishStorageMock.Setup(x => x.GetList()).Returns((List<DishDataModel>)null);
+
+            // Act & Assert
+            Assert.That(() => _dishBusinessLogic.GetAllDishes(), 
+                Throws.TypeOf<NullListException>());
+        }
+
+        [Test]
+        public void GetDishHistory_InvalidId_ThrowException_Test()
+        {
+            // Act & Assert
+            Assert.That(() => _dishBusinessLogic.GetDishHistory("invalid-guid"),
+                Throws.TypeOf<ValidationException>());
+        }
+
+        [Test]
+        public void GetDishById_ValidId_ReturnsDish_Test()
+        {
+            // Arrange
+            var dishId = Guid.NewGuid().ToString();
+            var testDish = new DishDataModel(dishId, "Борщ", DishType.Soup, 250.50, Guid.NewGuid().ToString());
+
+            _dishStorageMock.Setup(x => x.GetElementById(dishId))
+                .Returns(testDish);
+
+            // Act
+            var result = _dishBusinessLogic.GetDishById(dishId);
+
+            // Assert
+            Assert.That(result, Is.EqualTo(testDish));
+        }
+
+        [Test]
+        public void GetDishById_NotFound_ThrowException_Test()
+        {
+            // Arrange
+            var dishId = Guid.NewGuid().ToString();
+
+            // Act & Assert
+            Assert.That(() => _dishBusinessLogic.GetDishById(dishId),
+                Throws.TypeOf<ElementNotFoundException>());
+        }
+
+        [Test]
+        public void GetDishByName_ValidName_ReturnsDish_Test()
+        {
+            // Arrange
+            var dishName = "Борщ";
+            var testDish = new DishDataModel(Guid.NewGuid().ToString(), dishName, DishType.Soup, 250.50, Guid.NewGuid().ToString());
+
+            _dishStorageMock.Setup(x => x.GetElementByName(dishName))
+                .Returns(testDish);
+
+            // Act
+            var result = _dishBusinessLogic.GetDishByName(dishName);
+
+            // Assert
+            Assert.That(result, Is.EqualTo(testDish));
+        }
+
+        [Test]
+        public void InsertDish_ValidData_Success_Test()
+        {
+            // Arrange
+            var testDish = new DishDataModel(
+                Guid.NewGuid().ToString(),
+                "Борщ",
+                DishType.Soup,
+                250.50,
+                Guid.NewGuid().ToString());
+
+            // Act
+            _dishBusinessLogic.InsertDish(testDish);
+
+            // Assert
+            _dishStorageMock.Verify(x => x.AddElement(testDish), Times.Once);
+        }
+
+        [Test]
+        public void InsertDish_DuplicateName_ThrowException_Test()
+        {
+            // Arrange
+            var testDish = new DishDataModel(
+                Guid.NewGuid().ToString(),
+                "Борщ",
+                DishType.Soup,
+                250.50,
+                Guid.NewGuid().ToString());
+
+            _dishStorageMock.Setup(x => x.GetElementByName(testDish.Name))
+                .Returns(testDish);
+
+            // Act & Assert
+            Assert.That(() => _dishBusinessLogic.InsertDish(testDish),
+                Throws.TypeOf<ValidationException>());
+        }
+
+        [Test]
+        public void UpdateDish_ValidData_Success_Test()
+        {
+            // Arrange
+            var testDish = new DishDataModel(
+                Guid.NewGuid().ToString(),
+                "Борщ",
+                DishType.Soup,
+                250.50,
+                Guid.NewGuid().ToString());
+
+            _dishStorageMock.Setup(x => x.GetElementById(testDish.Id))
+                .Returns(testDish);
+
+            // Act
+            _dishBusinessLogic.UpdateDish(testDish);
+
+            // Assert
+            _dishStorageMock.Verify(x => x.UpdElement(testDish), Times.Once);
+        }
+
+        [Test]
+        public void DeleteDish_ValidId_Success_Test()
+        {
+            // Arrange
+            var dishId = Guid.NewGuid().ToString();
+            var testDish = new DishDataModel(
+                dishId,
+                "Борщ",
+                DishType.Soup,
+                250.50,
+                Guid.NewGuid().ToString());
+
+            _dishStorageMock.Setup(x => x.GetElementById(dishId))
+                .Returns(testDish);
+
+            // Act
+            _dishBusinessLogic.DeleteDish(dishId);
+
+            // Assert
+            _dishStorageMock.Verify(x => x.DelElement(dishId), Times.Once);
+        }
+
+        [Test]
+        public void DeleteDish_InvalidId_ThrowException_Test()
+        {
+            // Act & Assert
+            Assert.That(() => _dishBusinessLogic.DeleteDish("invalid-guid"),
+                Throws.TypeOf<ValidationException>());
+        }
+    }
+}

AndDietCokeProject/AndDietCokeTests/BusinessLogicsContractsTests/Dish_OrderBusinessLogicsContractsTests.cs

@@ -0,0 +1,313 @@
+using AndDietCokeBusinessLogic.Implementations;
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.StoragesContracts;
+using Microsoft.Extensions.Logging;
+using Moq;
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+
+namespace AndDietCokeTests.BusinessLogicsContractsTests
+{
+    [TestFixture]
+    internal class Dish_OrderBusinessLogicContractTests
+    {
+        private Dish_OrderBusinessLogicContract _dishOrderBusinessLogic;
+        private Mock<IDish_OrderStorageContract> _dishOrderStorageMock;
+        private Mock<ILogger<Dish_OrderBusinessLogicContract>> _loggerMock;
+
+        [OneTimeSetUp]
+        public void OneTimeSetUp()
+        {
+            _dishOrderStorageMock = new Mock<IDish_OrderStorageContract>();
+            _loggerMock = new Mock<ILogger<Dish_OrderBusinessLogicContract>>();
+            _dishOrderBusinessLogic = new Dish_OrderBusinessLogicContract(
+                _dishOrderStorageMock.Object,
+                _loggerMock.Object);
+        }
+
+        [SetUp]
+        public void SetUp()
+        {
+            _dishOrderStorageMock.Reset();
+            _loggerMock.Reset();
+        }
+
+        [Test]
+        public void GetAllDishOrders_ReturnListOfRecords_Test()
+        {
+            // Arrange
+            var testData = new List<Dish_OrderDataModel>
+            {
+                new(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 2),
+                new(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 1)
+            };
+
+            _dishOrderStorageMock.Setup(x => x.GetList(It.IsAny<string>(), It.IsAny<string>()))
+                .Returns(testData);
+
+            // Act
+            var result = _dishOrderBusinessLogic.GetAllDishOrders();
+
+            // Assert
+            Assert.Multiple(() =>
+            {
+                Assert.That(result, Is.Not.Null);
+                Assert.That(result, Is.EquivalentTo(testData));
+            });
+            _dishOrderStorageMock.Verify(x => x.GetList(null, null), Times.Once);
+        }
+
+        [Test]
+        public void GetAllDishOrders_WithOrderIdFilter_Test()
+        {
+            // Arrange
+            var orderId = Guid.NewGuid().ToString();
+            var testData = new List<Dish_OrderDataModel>
+            {
+                new(orderId, Guid.NewGuid().ToString(), 3)
+            };
+
+            _dishOrderStorageMock.Setup(x => x.GetList(orderId, It.IsAny<string>()))
+                .Returns(testData);
+
+            // Act
+            var result = _dishOrderBusinessLogic.GetAllDishOrders(orderId);
+
+            // Assert
+            Assert.That(result, Is.EquivalentTo(testData));
+            _dishOrderStorageMock.Verify(x => x.GetList(orderId, null), Times.Once);
+        }
+
+        [Test]
+        public void GetAllDishOrders_WithDishIdFilter_Test()
+        {
+            // Arrange
+            var dishId = Guid.NewGuid().ToString();
+            var testData = new List<Dish_OrderDataModel>
+            {
+                new(Guid.NewGuid().ToString(), dishId, 1)
+            };
+
+            _dishOrderStorageMock.Setup(x => x.GetList(It.IsAny<string>(), dishId))
+                .Returns(testData);
+
+            // Act
+            var result = _dishOrderBusinessLogic.GetAllDishOrders(null, dishId);
+
+            // Assert
+            Assert.That(result, Is.EquivalentTo(testData));
+            _dishOrderStorageMock.Verify(x => x.GetList(null, dishId), Times.Once);
+        }
+
+        [Test]
+        public void GetAllDishOrders_ReturnNull_ThrowException_Test()
+        {
+            // Arrange
+            _dishOrderStorageMock.Setup(x => x.GetList(It.IsAny<string>(), It.IsAny<string>()))
+                .Returns((List<Dish_OrderDataModel>)null);
+
+            // Act & Assert
+            Assert.That(() => _dishOrderBusinessLogic.GetAllDishOrders(),
+                Throws.TypeOf<NullListException>());
+        }
+
+        [Test]
+        public void GetAllDishOrders_InvalidOrderId_ThrowException_Test()
+        {
+            // Act & Assert
+            Assert.That(() => _dishOrderBusinessLogic.GetAllDishOrders("invalid-guid"),
+                Throws.TypeOf<ValidationException>());
+        }
+
+        [Test]
+        public void GetAllDishOrders_InvalidDishId_ThrowException_Test()
+        {
+            // Act & Assert
+            Assert.That(() => _dishOrderBusinessLogic.GetAllDishOrders(null, "invalid-guid"),
+                Throws.TypeOf<ValidationException>());
+        }
+
+        [Test]
+        public void GetDishOrderById_ValidIds_ReturnsRecord_Test()
+        {
+            // Arrange
+            var orderId = Guid.NewGuid().ToString();
+            var dishId = Guid.NewGuid().ToString();
+            var testRecord = new Dish_OrderDataModel(orderId, dishId, 2);
+
+            _dishOrderStorageMock.Setup(x => x.GetElementById(orderId, dishId))
+                .Returns(testRecord);
+
+            // Act
+            var result = _dishOrderBusinessLogic.GetDishOrderById(orderId, dishId);
+
+            // Assert
+            Assert.That(result, Is.EqualTo(testRecord));
+            _dishOrderStorageMock.Verify(x => x.GetElementById(orderId, dishId), Times.Once);
+        }
+
+        [Test]
+        public void GetDishOrderById_InvalidOrderId_ThrowException_Test()
+        {
+            // Act & Assert
+            Assert.That(() => _dishOrderBusinessLogic.GetDishOrderById("invalid", Guid.NewGuid().ToString()),
+                Throws.TypeOf<ValidationException>());
+        }
+
+        [Test]
+        public void GetDishOrderById_InvalidDishId_ThrowException_Test()
+        {
+            // Act & Assert
+            Assert.That(() => _dishOrderBusinessLogic.GetDishOrderById(Guid.NewGuid().ToString(), "invalid"),
+                Throws.TypeOf<ValidationException>());
+        }
+
+        [Test]
+        public void GetDishOrderById_NotFound_ThrowException_Test()
+        {
+            // Arrange
+            var orderId = Guid.NewGuid().ToString();
+            var dishId = Guid.NewGuid().ToString();
+
+            // Act & Assert
+            Assert.That(() => _dishOrderBusinessLogic.GetDishOrderById(orderId, dishId),
+                Throws.TypeOf<ElementNotFoundException>());
+        }
+
+        [Test]
+        public void InsertDishOrder_ValidData_Success_Test()
+        {
+            // Arrange
+            var testRecord = new Dish_OrderDataModel(
+                Guid.NewGuid().ToString(),
+                Guid.NewGuid().ToString(),
+                2);
+
+            // Act
+            _dishOrderBusinessLogic.InsertDishOrder(testRecord);
+
+            // Assert
+            _dishOrderStorageMock.Verify(x => x.AddElement(testRecord), Times.Once);
+        }
+
+        [Test]
+        public void InsertDishOrder_NullData_ThrowException_Test()
+        {
+            // Act & Assert
+            Assert.That(() => _dishOrderBusinessLogic.InsertDishOrder(null),
+                Throws.TypeOf<ArgumentNullException>());
+        }
+
+        [Test]
+        public void InsertDishOrder_InvalidCount_ThrowException_Test()
+        {
+            // Arrange
+            var invalidRecord = new Dish_OrderDataModel(
+                Guid.NewGuid().ToString(),
+                Guid.NewGuid().ToString(),
+                0); // Invalid count
+
+            // Act & Assert
+            Assert.That(() => _dishOrderBusinessLogic.InsertDishOrder(invalidRecord),
+                Throws.TypeOf<ValidationException>());
+        }
+
+        [Test]
+        public void InsertDishOrder_Duplicate_ThrowException_Test()
+        {
+            // Arrange
+            var testRecord = new Dish_OrderDataModel(
+                Guid.NewGuid().ToString(),
+                Guid.NewGuid().ToString(),
+                1);
+
+            _dishOrderStorageMock.Setup(x => x.GetElementById(testRecord.OrderId, testRecord.DishId))
+                .Returns(testRecord);
+
+            // Act & Assert
+            Assert.That(() => _dishOrderBusinessLogic.InsertDishOrder(testRecord),
+                Throws.TypeOf<ValidationException>());
+        }
+
+        [Test]
+        public void UpdateDishOrder_ValidData_Success_Test()
+        {
+            // Arrange
+            var testRecord = new Dish_OrderDataModel(
+                Guid.NewGuid().ToString(),
+                Guid.NewGuid().ToString(),
+                3);
+
+            _dishOrderStorageMock.Setup(x => x.GetElementById(testRecord.OrderId, testRecord.DishId))
+                .Returns(testRecord);
+
+            // Act
+            _dishOrderBusinessLogic.UpdateDishOrder(testRecord);
+
+            // Assert
+            _dishOrderStorageMock.Verify(x => x.UpdElement(testRecord), Times.Once);
+        }
+
+        [Test]
+        public void UpdateDishOrder_NotExists_ThrowException_Test()
+        {
+            // Arrange
+            var testRecord = new Dish_OrderDataModel(
+                Guid.NewGuid().ToString(),
+                Guid.NewGuid().ToString(),
+                2);
+
+            // Act & Assert
+            Assert.That(() => _dishOrderBusinessLogic.UpdateDishOrder(testRecord),
+                Throws.TypeOf<ElementNotFoundException>());
+        }
+
+        [Test]
+        public void DeleteDishOrder_ValidIds_Success_Test()
+        {
+            // Arrange
+            var orderId = Guid.NewGuid().ToString();
+            var dishId = Guid.NewGuid().ToString();
+            var testRecord = new Dish_OrderDataModel(orderId, dishId, 1);
+
+            _dishOrderStorageMock.Setup(x => x.GetElementById(orderId, dishId))
+                .Returns(testRecord);
+
+            // Act
+            _dishOrderBusinessLogic.DeleteDishOrder(orderId, dishId);
+
+            // Assert
+            _dishOrderStorageMock.Verify(x => x.DelElement(orderId, dishId), Times.Once);
+        }
+
+        [Test]
+        public void DeleteDishOrder_NotExists_ThrowException_Test()
+        {
+            // Arrange
+            var orderId = Guid.NewGuid().ToString();
+            var dishId = Guid.NewGuid().ToString();
+
+            // Act & Assert
+            Assert.That(() => _dishOrderBusinessLogic.DeleteDishOrder(orderId, dishId),
+                Throws.TypeOf<ElementNotFoundException>());
+        }
+
+        [Test]
+        public void DeleteDishOrder_InvalidOrderId_ThrowException_Test()
+        {
+            // Act & Assert
+            Assert.That(() => _dishOrderBusinessLogic.DeleteDishOrder("invalid", Guid.NewGuid().ToString()),
+                Throws.TypeOf<ValidationException>());
+        }
+
+        [Test]
+        public void DeleteDishOrder_InvalidDishId_ThrowException_Test()
+        {
+            // Act & Assert
+            Assert.That(() => _dishOrderBusinessLogic.DeleteDishOrder(Guid.NewGuid().ToString(), "invalid"),
+                Throws.TypeOf<ValidationException>());
+        }
+    }
+}

AndDietCokeProject/AndDietCokeTests/BusinessLogicsContractsTests/EmployeeBusinessLogicContractTests.cs

@@ -0,0 +1,268 @@
+using AndDietCokeBusinessLogic.Implementations;
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Enums;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.Extensions;
+using AndDietCokeContracts.StoragesContracts;
+using Microsoft.Extensions.Logging;
+using Moq;
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+
+namespace AndDietCokeTests.BusinessLogicsContractsTests;
+
+[TestFixture]
+internal class EmployeeBusinessLogicContractTests
+{
+    private EmployeeBusinessLogicContract _employeeBusinessLogicContract;
+    private Mock<IEmployeeStoragesContracts> _employeeStorageContract;
+    private Mock<ILogger<EmployeeBusinessLogicContract>> _logger;
+
+    [OneTimeSetUp]
+    public void OneTimeSetUp()
+    {
+        _employeeStorageContract = new Mock<IEmployeeStoragesContracts>();
+        _logger = new Mock<ILogger<EmployeeBusinessLogicContract>>();
+        _employeeBusinessLogicContract = new EmployeeBusinessLogicContract(
+            _employeeStorageContract.Object,
+            _logger.Object);
+    }
+
+    [SetUp]
+    public void SetUp()
+    {
+        _employeeStorageContract.Reset();
+        _logger.Reset();
+    }
+
+    [Test]
+    public void GetAllEmployees_ReturnListOfRecords_Test()
+    {
+        // Arrange
+        var testEmployees = new List<EmployeeDataModel>
+        {
+            new(Guid.NewGuid().ToString(), "Иванов И.И.", Guid.NewGuid().ToString(),
+                PositionType.Manager, DateTime.Now.AddYears(-30), DateTime.Now.AddYears(-5), false),
+            new(Guid.NewGuid().ToString(), "Петров П.П.", Guid.NewGuid().ToString(),
+                PositionType.Developer, DateTime.Now.AddYears(-25), DateTime.Now.AddYears(-3), true)
+        };
+
+        _employeeStorageContract.Setup(x => x.GetList(
+            It.IsAny<bool>(), It.IsAny<string>(),
+            It.IsAny<DateTime?>(), It.IsAny<DateTime?>(),
+            It.IsAny<DateTime?>(), It.IsAny<DateTime?>()))
+            .Returns(testEmployees);
+
+        // Act
+        var resultActive = _employeeBusinessLogicContract.GetAllEmployees(true);
+        var resultAll = _employeeBusinessLogicContract.GetAllEmployees(false);
+
+        // Assert
+        Assert.Multiple(() =>
+        {
+            Assert.That(resultActive, Is.Not.Null);
+            Assert.That(resultAll, Is.Not.Null);
+            Assert.That(resultActive, Is.EquivalentTo(testEmployees));
+            Assert.That(resultAll, Is.EquivalentTo(testEmployees));
+        });
+
+        _employeeStorageContract.Verify(x => x.GetList(true, null, null, null, null, null), Times.Once);
+        _employeeStorageContract.Verify(x => x.GetList(false, null, null, null, null, null), Times.Once);
+    }
+
+    [Test]
+    public void GetAllEmployees_WithPositionFilter_Test()
+    {
+        // Arrange
+        var positionId = Guid.NewGuid().ToString();
+        var testEmployees = new List<EmployeeDataModel>
+        {
+            new(Guid.NewGuid().ToString(), "Сидоров С.С.", positionId,
+                PositionType.Developer, DateTime.Now.AddYears(-28), DateTime.Now.AddYears(-4), false)
+        };
+
+        _employeeStorageContract.Setup(x => x.GetList(
+            It.IsAny<bool>(), positionId,
+            It.IsAny<DateTime?>(), It.IsAny<DateTime?>(),
+            It.IsAny<DateTime?>(), It.IsAny<DateTime?>()))
+            .Returns(testEmployees);
+
+        // Act
+        var result = _employeeBusinessLogicContract.GetAllEmployees(true, positionId);
+
+        // Assert
+        Assert.That(result, Is.EquivalentTo(testEmployees));
+        _employeeStorageContract.Verify(x => x.GetList(true, positionId, null, null, null, null), Times.Once);
+    }
+
+    [Test]
+    public void GetAllEmployees_WithDateFilters_Test()
+    {
+        // Arrange
+        var fromDate = DateTime.Now.AddYears(-5);
+        var toDate = DateTime.Now;
+        var testEmployees = new List<EmployeeDataModel>
+        {
+            new(Guid.NewGuid().ToString(), "Кузнецов К.К.", Guid.NewGuid().ToString(),
+                PositionType.QA, DateTime.Now.AddYears(-35), DateTime.Now.AddYears(-2), false)
+        };
+
+        _employeeStorageContract.Setup(x => x.GetList(
+            It.IsAny<bool>(), It.IsAny<string>(),
+            fromDate, toDate,
+            fromDate, toDate))
+            .Returns(testEmployees);
+
+        // Act
+        var result = _employeeBusinessLogicContract.GetAllEmployees(
+            true, null, fromDate, toDate, fromDate, toDate);
+
+        // Assert
+        Assert.That(result, Is.EquivalentTo(testEmployees));
+        _employeeStorageContract.Verify(x => x.GetList(
+            true, null, fromDate, toDate, fromDate, toDate), Times.Once);
+    }
+
+    [Test]
+    public void GetAllEmployees_ReturnNull_ThrowsException_Test()
+    {
+        // Arrange
+        _employeeStorageContract.Setup(x => x.GetList(
+            It.IsAny<bool>(), It.IsAny<string>(),
+            It.IsAny<DateTime?>(), It.IsAny<DateTime?>(),
+            It.IsAny<DateTime?>(), It.IsAny<DateTime?>()))
+            .Returns((List<EmployeeDataModel>)null);
+
+        // Act & Assert
+        Assert.That(() => _employeeBusinessLogicContract.GetAllEmployees(),
+            Throws.TypeOf<NullListException>());
+    }
+
+    [Test]
+    public void GetEmployeeById_ValidId_ReturnsEmployee_Test()
+    {
+        // Arrange
+        var employeeId = Guid.NewGuid().ToString();
+        var testEmployee = new EmployeeDataModel(
+            employeeId, "Иванов И.И.", Guid.NewGuid().ToString(),
+            PositionType.Manager, DateTime.Now.AddYears(-30), DateTime.Now.AddYears(-5), false);
+
+        _employeeStorageContract.Setup(x => x.GetElementById(employeeId))
+            .Returns(testEmployee);
+
+        // Act
+        var result = _employeeBusinessLogicContract.GetEmployeeById(employeeId);
+
+        // Assert
+        Assert.That(result, Is.EqualTo(testEmployee));
+        _employeeStorageContract.Verify(x => x.GetElementById(employeeId), Times.Once);
+    }
+
+    [Test]
+    public void GetEmployeeById_InvalidId_ThrowsException_Test()
+    {
+        // Arrange
+        var invalidId = "not-a-guid";
+
+        // Act & Assert
+        Assert.That(() => _employeeBusinessLogicContract.GetEmployeeById(invalidId),
+            Throws.TypeOf<ValidationException>());
+    }
+
+    [Test]
+    public void GetEmployeeByFIO_ValidFIO_ReturnsEmployee_Test()
+    {
+        // Arrange
+        var fio = "Иванов И.И.";
+        var testEmployee = new EmployeeDataModel(
+            Guid.NewGuid().ToString(), fio, Guid.NewGuid().ToString(),
+            PositionType.Manager, DateTime.Now.AddYears(-30), DateTime.Now.AddYears(-5), false);
+
+        _employeeStorageContract.Setup(x => x.GetElementByFIO(fio))
+            .Returns(testEmployee);
+
+        // Act
+        var result = _employeeBusinessLogicContract.GetEmployeeByFIO(fio);
+
+        // Assert
+        Assert.That(result, Is.EqualTo(testEmployee));
+        _employeeStorageContract.Verify(x => x.GetElementByFIO(fio), Times.Once);
+    }
+
+    [Test]
+    public void InsertEmployee_ValidEmployee_Success_Test()
+    {
+        // Arrange
+        var testEmployee = new EmployeeDataModel(
+            Guid.NewGuid().ToString(), "Иванов И.И.", Guid.NewGuid().ToString(),
+            PositionType.Manager, DateTime.Now.AddYears(-30), DateTime.Now.AddYears(-5), false);
+
+        // Act
+        _employeeBusinessLogicContract.InsertEmployee(testEmployee);
+
+        // Assert
+        _employeeStorageContract.Verify(x => x.AddElement(testEmployee), Times.Once);
+    }
+
+    [Test]
+    public void InsertEmployee_InvalidEmployee_ThrowsException_Test()
+    {
+        // Arrange
+        var invalidEmployee = new EmployeeDataModel(
+            "invalid-id", "Иванов", "invalid-post",
+            PositionType.None, DateTime.Now, DateTime.Now, false);
+
+        // Act & Assert
+        Assert.That(() => _employeeBusinessLogicContract.InsertEmployee(invalidEmployee),
+            Throws.TypeOf<ValidationException>());
+    }
+
+    [Test]
+    public void UpdateEmployee_ValidEmployee_Success_Test()
+    {
+        // Arrange
+        var testEmployee = new EmployeeDataModel(
+            Guid.NewGuid().ToString(), "Иванов И.И.", Guid.NewGuid().ToString(),
+            PositionType.Manager, DateTime.Now.AddYears(-30), DateTime.Now.AddYears(-5), false);
+
+        _employeeStorageContract.Setup(x => x.GetElementById(testEmployee.Id))
+            .Returns(testEmployee);
+
+        // Act
+        _employeeBusinessLogicContract.UpdateEmployee(testEmployee);
+
+        // Assert
+        _employeeStorageContract.Verify(x => x.UpdElement(testEmployee), Times.Once);
+    }
+
+    [Test]
+    public void DeleteEmployee_ValidId_Success_Test()
+    {
+        // Arrange
+        var employeeId = Guid.NewGuid().ToString();
+        var testEmployee = new EmployeeDataModel(
+            employeeId, "Иванов И.И.", Guid.NewGuid().ToString(),
+            PositionType.Manager, DateTime.Now.AddYears(-30), DateTime.Now.AddYears(-5), false);
+
+        _employeeStorageContract.Setup(x => x.GetElementById(employeeId))
+            .Returns(testEmployee);
+
+        // Act
+        _employeeBusinessLogicContract.DeleteEmployee(employeeId);
+
+        // Assert
+        _employeeStorageContract.Verify(x => x.DelElement(employeeId), Times.Once);
+    }
+
+    [Test]
+    public void DeleteEmployee_InvalidId_ThrowsException_Test()
+    {
+        // Arrange
+        var invalidId = "not-a-guid";
+
+        // Act & Assert
+        Assert.That(() => _employeeBusinessLogicContract.DeleteEmployee(invalidId),
+            Throws.TypeOf<ValidationException>());
+    }
+}

AndDietCokeProject/AndDietCokeTests/BusinessLogicsContractsTests/OrderBusinessLogicContractTests.cs

@@ -0,0 +1,179 @@
+using AndDietCokeBusinessLogic.Implementations;
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.StorageContracts;
+using Microsoft.Extensions.Logging;
+using Moq;
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+
+namespace AndDietCokeTests.BusinessLogicsContractsTests
+{
+    [TestFixture]
+    internal class OrderBusinessLogicContractTests
+    {
+        private OrderBusinessLogicContract _orderBusinessLogic;
+        private Mock<IOrderStorageContracts> _orderStorageMock;
+        private Mock<ILogger<OrderBusinessLogicContract>> _loggerMock;
+
+        [OneTimeSetUp]
+        public void OneTimeSetUp()
+        {
+            _orderStorageMock = new Mock<IOrderStorageContracts>();
+            _loggerMock = new Mock<ILogger<OrderBusinessLogicContract>>();
+            _orderBusinessLogic = new OrderBusinessLogicContract(
+                _orderStorageMock.Object,
+                _loggerMock.Object);
+        }
+
+        [SetUp]
+        public void SetUp()
+        {
+            _orderStorageMock.Reset();
+            _loggerMock.Reset();
+        }
+
+        [Test]
+        public void GetAllOrders_ReturnListOfRecords_Test()
+        {
+            // Arrange
+            var testOrders = new List<OrderDataModels>
+            {
+                new(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), Guid.NewGuid().ToString(),
+                    new List<Dish_OrderDataModel> { new(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 1) }),
+                new(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), Guid.NewGuid().ToString(),
+                    new List<Dish_OrderDataModel> { new(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 2) })
+            };
+
+            _orderStorageMock.Setup(x => x.GetList(It.IsAny<string>(), It.IsAny<string>(), It.IsAny<string>()))
+                .Returns(testOrders);
+
+            // Act
+            var result = _orderBusinessLogic.GetAllOrders();
+
+            // Assert
+            Assert.Multiple(() =>
+            {
+                Assert.That(result, Is.Not.Null);
+                Assert.That(result, Is.EquivalentTo(testOrders));
+            });
+            _orderStorageMock.Verify(x => x.GetList(null, null, null), Times.Once);
+        }
+
+        [Test]
+        public void GetAllOrders_WithClientFilter_Test()
+        {
+            // Arrange
+            var clientId = Guid.NewGuid().ToString();
+            var testOrders = new List<OrderDataModels>
+            {
+                new(Guid.NewGuid().ToString(), clientId, Guid.NewGuid().ToString(),
+                    new List<Dish_OrderDataModel> { new(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 1) })
+            };
+
+            _orderStorageMock.Setup(x => x.GetList(clientId, It.IsAny<string>(), It.IsAny<string>()))
+                .Returns(testOrders);
+
+            // Act
+            var result = _orderBusinessLogic.GetAllOrders(clientId: clientId);
+
+            // Assert
+            Assert.That(result, Is.EquivalentTo(testOrders));
+            _orderStorageMock.Verify(x => x.GetList(clientId, null, null), Times.Once);
+        }
+
+        [Test]
+        public void GetAllOrders_InvalidClientId_ThrowException_Test()
+        {
+            // Act & Assert
+            Assert.That(() => _orderBusinessLogic.GetAllOrders(clientId: "invalid-guid"),
+                Throws.TypeOf<ValidationException>());
+        }
+
+        [Test]
+        public void GetOrderById_ValidId_ReturnsOrder_Test()
+        {
+            // Arrange
+            var orderId = Guid.NewGuid().ToString();
+            var testOrder = new OrderDataModels(
+                orderId,
+                Guid.NewGuid().ToString(),
+                Guid.NewGuid().ToString(),
+                new List<Dish_OrderDataModel> { new(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 1) });
+
+            _orderStorageMock.Setup(x => x.GetElementById(orderId))
+                .Returns(testOrder);
+
+            // Act
+            var result = _orderBusinessLogic.GetOrderById(orderId);
+
+            // Assert
+            Assert.That(result, Is.EqualTo(testOrder));
+        }
+
+        [Test]
+        public void GetOrderById_InvalidId_ThrowException_Test()
+        {
+            // Act & Assert
+            Assert.That(() => _orderBusinessLogic.GetOrderById("invalid-guid"),
+                Throws.TypeOf<ValidationException>());
+        }
+
+        [Test]
+        public void InsertOrder_ValidData_Success_Test()
+        {
+            // Arrange
+            var testOrder = new OrderDataModels(
+                Guid.NewGuid().ToString(),
+                Guid.NewGuid().ToString(),
+                Guid.NewGuid().ToString(),
+                new List<Dish_OrderDataModel> { new(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 1) });
+
+            // Act
+            _orderBusinessLogic.InsertOrder(testOrder);
+
+            // Assert
+            _orderStorageMock.Verify(x => x.AddElement(testOrder), Times.Once);
+        }
+
+        [Test]
+        public void InsertOrder_DuplicateId_ThrowException_Test()
+        {
+            // Arrange
+            var testOrder = new OrderDataModels(
+                Guid.NewGuid().ToString(),
+                Guid.NewGuid().ToString(),
+                Guid.NewGuid().ToString(),
+                new List<Dish_OrderDataModel> { new(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 1) });
+
+            _orderStorageMock.Setup(x => x.GetElementById(testOrder.Id))
+                .Returns(testOrder);
+
+            // Act & Assert
+            Assert.That(() => _orderBusinessLogic.InsertOrder(testOrder),
+                Throws.TypeOf<ValidationException>());
+        }
+
+        [Test]
+        public void DeleteOrder_ValidId_Success_Test()
+        {
+            // Arrange
+            var orderId = Guid.NewGuid().ToString();
+            var testOrder = new OrderDataModels(
+                orderId,
+                Guid.NewGuid().ToString(),
+                Guid.NewGuid().ToString(),
+                new List<Dish_OrderDataModel> { new(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 1) });
+
+            _orderStorageMock.Setup(x => x.GetElementById(orderId))
+                .Returns(testOrder);
+
+            // Act
+            _orderBusinessLogic.DeleteOrder(orderId);
+
+            // Assert
+            _orderStorageMock.Verify(x => x.DelElement(orderId), Times.Once);
+        }
+    }
+}

AndDietCokeProject/AndDietCokeTests/BusinessLogicsContractsTests/PositionBusinessLogicsContractsTests.cs

@@ -0,0 +1,454 @@
+using AndDietCokeBusinessLogic.Implementations;
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Enums;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.StoragesContracts;
+using Microsoft.Extensions.Logging;
+using Moq;
+
+namespace AndDietCokeTests.BusinessLogicsContractsTests;
+
+[TestFixture]
+internal class PositionBusinessLogicContractTests
+{
+    private PositionBusinessLogicContract _positionBusinessLogicContract;
+    private Mock<IPositionStorageContract> _positionStorageContract;
+
+    [OneTimeSetUp]
+    public void OneTimeSetUp()
+    {
+        _positionStorageContract = new Mock<IPositionStorageContract>();
+        _positionBusinessLogicContract = new PositionBusinessLogicContract(_positionStorageContract.Object, new Mock<ILogger>().Object);
+    }
+
+    [TearDown]
+    public void SetUp()
+    {
+        _positionStorageContract.Reset();
+    }
+
+    [Test]
+    public void GetAllPositions_ReturnListOfRecords_Test()
+    {
+        //Arrange
+        var listOriginal = new List<PositionDataModel>()
+        {
+            new(Guid.NewGuid().ToString(),"name 1", PositionType.Assistant, 10, true, DateTime.UtcNow),
+            new(Guid.NewGuid().ToString(), "name 2", PositionType.Assistant, 10, false, DateTime.UtcNow),
+            new(Guid.NewGuid().ToString(), "name 3", PositionType.Assistant, 10, true, DateTime.UtcNow),
+        };
+        _positionStorageContract.Setup(x => x.GetList(It.IsAny<bool>())).Returns(listOriginal);
+        //Act
+        var listOnlyActive = _positionBusinessLogicContract.GetAllPositions(true);
+        var listAll = _positionBusinessLogicContract.GetAllPositions(false);
+        //Assert
+        Assert.Multiple(() =>
+        {
+            Assert.That(listOnlyActive, Is.Not.Null);
+            Assert.That(listAll, Is.Not.Null);
+            Assert.That(listOnlyActive, Is.EquivalentTo(listOriginal));
+            Assert.That(listAll, Is.EquivalentTo(listOriginal));
+        });
+        _positionStorageContract.Verify(x => x.GetList(true), Times.Once);
+        _positionStorageContract.Verify(x => x.GetList(false), Times.Once);
+    }
+
+    [Test]
+    public void GetAllPositions_ReturnEmptyList_Test()
+    {
+        //Arrange
+        _positionStorageContract.Setup(x => x.GetList(It.IsAny<bool>())).Returns([]);
+        //Act
+        var listOnlyActive = _positionBusinessLogicContract.GetAllPositions(true);
+        var listAll = _positionBusinessLogicContract.GetAllPositions(false);
+        //Assert
+        Assert.Multiple(() =>
+        {
+            Assert.That(listOnlyActive, Is.Not.Null);
+            Assert.That(listAll, Is.Not.Null);
+            Assert.That(listOnlyActive, Has.Count.EqualTo(0));
+            Assert.That(listAll, Has.Count.EqualTo(0));
+        });
+        _positionStorageContract.Verify(x => x.GetList(It.IsAny<bool>()), Times.Exactly(2));
+    }
+
+    [Test]
+    public void GetAllPositions_ReturnNull_ThrowException_Test()
+    {
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.GetAllPositions(It.IsAny<bool>()), Throws.TypeOf<NullListException>());
+        _positionStorageContract.Verify(x => x.GetList(It.IsAny<bool>()), Times.Once);
+    }
+
+    [Test]
+    public void GetAllPositions_StorageThrowError_ThrowException_Test()
+    {
+        //Arrange
+        _positionStorageContract.Setup(x => x.GetList(It.IsAny<bool>())).Throws(new StorageException(new InvalidOperationException()));
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.GetAllPositions(It.IsAny<bool>()), Throws.TypeOf<StorageException>());
+        _positionStorageContract.Verify(x => x.GetList(It.IsAny<bool>()), Times.Once);
+    }
+
+    [Test]
+    public void GetAllDataOfPosition_ReturnListOfRecords_Test()
+    {
+        //Arrange
+        var PositionId = Guid.NewGuid().ToString();
+        var listOriginal = new List<PositionDataModel>()
+        {
+            new(PositionId, "name 1", PositionType.Assistant, 10, true, DateTime.UtcNow),
+            new(PositionId, "name 2", PositionType.Assistant, 10, false, DateTime.UtcNow)
+        };
+        _positionStorageContract.Setup(x => x.GetPostWithHistory(It.IsAny<string>())).Returns(listOriginal);
+        //Act
+        var list = _positionBusinessLogicContract.GetAllDataOfPosition(PositionId);
+        //Assert
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(2));
+        _positionStorageContract.Verify(x => x.GetPostWithHistory(PositionId), Times.Once);
+    }
+
+    [Test]
+    public void GetAllDataOfPosition_ReturnEmptyList_Test()
+    {
+        //Arrange
+        _positionStorageContract.Setup(x => x.GetPostWithHistory(It.IsAny<string>())).Returns([]);
+        //Act
+        var list = _positionBusinessLogicContract.GetAllDataOfPosition(Guid.NewGuid().ToString());
+        //Assert
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(0));
+        _positionStorageContract.Verify(x => x.GetPostWithHistory(It.IsAny<string>()), Times.Once);
+    }
+
+    [Test]
+    public void GetAllDataOfPosition_PositionIdIsNullOrEmpty_ThrowException_Test()
+    {
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.GetAllDataOfPosition(null), Throws.TypeOf<ArgumentNullException>());
+        Assert.That(() => _positionBusinessLogicContract.GetAllDataOfPosition(string.Empty), Throws.TypeOf<ArgumentNullException>());
+        _positionStorageContract.Verify(x => x.GetPostWithHistory(It.IsAny<string>()), Times.Never);
+    }
+
+    [Test]
+    public void GetAllDataOfPosition_PositionIdIsNotGuid_ThrowException_Test()
+    {
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.GetAllDataOfPosition("id"), Throws.TypeOf<ValidationException>());
+        _positionStorageContract.Verify(x => x.GetPostWithHistory(It.IsAny<string>()), Times.Never);
+    }
+
+    [Test]
+    public void GetAllDataOfPosition_ReturnNull_ThrowException_Test()
+    {
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.GetAllDataOfPosition(Guid.NewGuid().ToString()), Throws.TypeOf<NullListException>());
+        _positionStorageContract.Verify(x => x.GetPostWithHistory(It.IsAny<string>()), Times.Once);
+    }
+
+    [Test]
+    public void GetAllDataOfPosition_StorageThrowError_ThrowException_Test()
+    {
+        //Arrange
+        _positionStorageContract.Setup(x => x.GetPostWithHistory(It.IsAny<string>())).Throws(new StorageException(new InvalidOperationException()));
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.GetAllDataOfPosition(Guid.NewGuid().ToString()), Throws.TypeOf<StorageException>());
+        _positionStorageContract.Verify(x => x.GetPostWithHistory(It.IsAny<string>()), Times.Once);
+    }
+
+    [Test]
+    public void GetPositionByData_GetById_ReturnRecord_Test()
+    {
+        //Arrange
+        var id = Guid.NewGuid().ToString();
+        var record = new PositionDataModel(id, "name", PositionType.Assistant, 10, true, DateTime.UtcNow);
+        _positionStorageContract.Setup(x => x.GetElementById(id)).Returns(record);
+        //Act
+        var element = _positionBusinessLogicContract.GetPositionByData(id);
+        //Assert
+        Assert.That(element, Is.Not.Null);
+        Assert.That(element.Id, Is.EqualTo(id));
+        _positionStorageContract.Verify(x => x.GetElementById(It.IsAny<string>()), Times.Once);
+    }
+
+    [Test]
+    public void GetPositionByData_GetByName_ReturnRecord_Test()
+    {
+        //Arrange
+        var PositionName = "name";
+        var record = new PositionDataModel(Guid.NewGuid().ToString(), PositionName, PositionType.Assistant, 10, true, DateTime.UtcNow);
+        _positionStorageContract.Setup(x => x.GetElementByName(PositionName)).Returns(record);
+        //Act
+        var element = _positionBusinessLogicContract.GetPositionByData(PositionName);
+        //Assert
+        Assert.That(element, Is.Not.Null);
+        Assert.That(element.PositionName, Is.EqualTo(PositionName));
+        _positionStorageContract.Verify(x => x.GetElementByName(It.IsAny<string>()), Times.Once);
+    }
+
+    [Test]
+    public void GetPositionByData_EmptyData_ThrowException_Test()
+    {
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.GetPositionByData(null), Throws.TypeOf<ArgumentNullException>());
+        Assert.That(() => _positionBusinessLogicContract.GetPositionByData(string.Empty), Throws.TypeOf<ArgumentNullException>());
+        _positionStorageContract.Verify(x => x.GetElementById(It.IsAny<string>()), Times.Never);
+        _positionStorageContract.Verify(x => x.GetElementByName(It.IsAny<string>()), Times.Never);
+    }
+
+    [Test]
+    public void GetPositionByData_GetById_NotFoundRecord_ThrowException_Test()
+    {
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.GetPositionByData(Guid.NewGuid().ToString()), Throws.TypeOf<ElementNotFoundException>());
+        _positionStorageContract.Verify(x => x.GetElementById(It.IsAny<string>()), Times.Once);
+        _positionStorageContract.Verify(x => x.GetElementByName(It.IsAny<string>()), Times.Never);
+    }
+
+    [Test]
+    public void GetPositionByData_GetByName_NotFoundRecord_ThrowException_Test()
+    {
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.GetPositionByData("name"), Throws.TypeOf<ElementNotFoundException>());
+        _positionStorageContract.Verify(x => x.GetElementById(It.IsAny<string>()), Times.Never);
+        _positionStorageContract.Verify(x => x.GetElementByName(It.IsAny<string>()), Times.Once);
+    }
+
+    [Test]
+    public void GetPositionByData_StorageThrowError_ThrowException_Test()
+    {
+        //Arrange
+        _positionStorageContract.Setup(x => x.GetElementById(It.IsAny<string>())).Throws(new StorageException(new InvalidOperationException()));
+        _positionStorageContract.Setup(x => x.GetElementByName(It.IsAny<string>())).Throws(new StorageException(new InvalidOperationException()));
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.GetPositionByData(Guid.NewGuid().ToString()), Throws.TypeOf<StorageException>());
+        Assert.That(() => _positionBusinessLogicContract.GetPositionByData("name"), Throws.TypeOf<StorageException>());
+        _positionStorageContract.Verify(x => x.GetElementById(It.IsAny<string>()), Times.Once);
+        _positionStorageContract.Verify(x => x.GetElementByName(It.IsAny<string>()), Times.Once);
+    }
+
+    [Test]
+    public void InsertPosition_CorrectRecord_Test()
+    {
+        //Arrange
+        var flag = false;
+        var record = new PositionDataModel(Guid.NewGuid().ToString(), "name", PositionType.Assistant, 10, true, DateTime.UtcNow.AddDays(-1));
+        _positionStorageContract.Setup(x => x.AddElement(It.IsAny<PositionDataModel>()))
+            .Callback((PositionDataModel x) =>
+            {
+                flag = x.Id == record.Id && x.PositionName == record.PositionName && x.PositionType == record.PositionType && x.Salary == record.Salary &&
+                    x.ChangeDate == record.ChangeDate;
+            });
+        //Act
+        _positionBusinessLogicContract.InsertPosition(record);
+        //Assert
+        _positionStorageContract.Verify(x => x.AddElement(It.IsAny<PositionDataModel>()), Times.Once);
+        Assert.That(flag);
+    }
+
+    [Test]
+    public void InsertPosition_RecordWithExistsData_ThrowException_Test()
+    {
+        //Arrange
+        _positionStorageContract.Setup(x => x.AddElement(It.IsAny<PositionDataModel>())).Throws(new ElementExistsException("Data", "Data"));
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.InsertPosition(new(Guid.NewGuid().ToString(), "name", PositionType.Assistant, 10, true, DateTime.UtcNow)), Throws.TypeOf<ElementExistsException>());
+        _positionStorageContract.Verify(x => x.AddElement(It.IsAny<PositionDataModel>()), Times.Once);
+    }
+
+    [Test]
+    public void InsertPosition_NullRecord_ThrowException_Test()
+    {
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.InsertPosition(null), Throws.TypeOf<ArgumentNullException>());
+        _positionStorageContract.Verify(x => x.AddElement(It.IsAny<PositionDataModel>()), Times.Never);
+    }
+
+    [Test]
+    public void InsertPosition_InvalidRecord_ThrowException_Test()
+    {
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.InsertPosition(new PositionDataModel("id", "name", PositionType.Assistant, 10, true, DateTime.UtcNow)), Throws.TypeOf<ValidationException>());
+        _positionStorageContract.Verify(x => x.AddElement(It.IsAny<PositionDataModel>()), Times.Never);
+    }
+
+    [Test]
+    public void InsertPosition_StorageThrowError_ThrowException_Test()
+    {
+        //Arrange
+        _positionStorageContract.Setup(x => x.AddElement(It.IsAny<PositionDataModel>())).Throws(new StorageException(new InvalidOperationException()));
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.InsertPosition(new(Guid.NewGuid().ToString(), "name", PositionType.Assistant, 10, true, DateTime.UtcNow)), Throws.TypeOf<StorageException>());
+        _positionStorageContract.Verify(x => x.AddElement(It.IsAny<PositionDataModel>()), Times.Once);
+    }
+
+    [Test]
+    public void UpdatePosition_CorrectRecord_Test()
+    {
+        //Arrange
+        var flag = false;
+        var record = new PositionDataModel(Guid.NewGuid().ToString(), "name", PositionType.Assistant, 10, true, DateTime.UtcNow.AddDays(-1));
+        _positionStorageContract.Setup(x => x.UpdElement(It.IsAny<PositionDataModel>()))
+            .Callback((PositionDataModel x) =>
+            {
+                flag = x.Id == record.Id && x.PositionName == record.PositionName && x.PositionType == record.PositionType && x.Salary == record.Salary &&
+                    x.ChangeDate == record.ChangeDate;
+            });
+        //Act
+        _positionBusinessLogicContract.UpdatePosition(record);
+        //Assert
+        _positionStorageContract.Verify(x => x.UpdElement(It.IsAny<PositionDataModel>()), Times.Once);
+        Assert.That(flag);
+    }
+
+    [Test]
+    public void UpdatePosition_RecordWithIncorrectData_ThrowException_Test()
+    {
+        //Arrange
+        _positionStorageContract.Setup(x => x.UpdElement(It.IsAny<PositionDataModel>())).Throws(new ElementNotFoundException(""));
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.UpdatePosition(new(Guid.NewGuid().ToString(), "name", PositionType.Assistant, 10, true, DateTime.UtcNow)), Throws.TypeOf<ElementNotFoundException>());
+        _positionStorageContract.Verify(x => x.UpdElement(It.IsAny<PositionDataModel>()), Times.Once);
+    }
+
+    [Test]
+    public void UpdatePosition_RecordWithExistsData_ThrowException_Test()
+    {
+        //Arrange
+        _positionStorageContract.Setup(x => x.UpdElement(It.IsAny<PositionDataModel>())).Throws(new ElementExistsException("Data", "Data"));
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.UpdatePosition(new(Guid.NewGuid().ToString(), "anme", PositionType.Assistant, 10, true, DateTime.UtcNow)), Throws.TypeOf<ElementExistsException>());
+        _positionStorageContract.Verify(x => x.UpdElement(It.IsAny<PositionDataModel>()), Times.Once);
+    }
+
+    [Test]
+    public void UpdatePosition_NullRecord_ThrowException_Test()
+    {
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.UpdatePosition(null), Throws.TypeOf<ArgumentNullException>());
+        _positionStorageContract.Verify(x => x.UpdElement(It.IsAny<PositionDataModel>()), Times.Never);
+    }
+
+    [Test]
+    public void UpdatePosition_InvalidRecord_ThrowException_Test()
+    {
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.UpdatePosition(new PositionDataModel("id", "name", PositionType.Assistant, 10, true, DateTime.UtcNow)), Throws.TypeOf<ValidationException>());
+        _positionStorageContract.Verify(x => x.UpdElement(It.IsAny<PositionDataModel>()), Times.Never);
+    }
+
+    [Test]
+    public void UpdatePosition_StorageThrowError_ThrowException_Test()
+    {
+        //Arrange
+        _positionStorageContract.Setup(x => x.UpdElement(It.IsAny<PositionDataModel>())).Throws(new StorageException(new InvalidOperationException()));
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.UpdatePosition(new(Guid.NewGuid().ToString(), "name", PositionType.Assistant, 10, true, DateTime.UtcNow)), Throws.TypeOf<StorageException>());
+        _positionStorageContract.Verify(x => x.UpdElement(It.IsAny<PositionDataModel>()), Times.Once);
+    }
+
+    [Test]
+    public void DeletePosition_CorrectRecord_Test()
+    {
+        //Arrange
+        var id = Guid.NewGuid().ToString();
+        var flag = false;
+        _positionStorageContract.Setup(x => x.DelElement(It.Is((string x) => x == id))).Callback(() => { flag = true; });
+        //Act
+        _positionBusinessLogicContract.DeletePosition(id);
+        //Assert
+        _positionStorageContract.Verify(x => x.DelElement(It.IsAny<string>()), Times.Once);
+        Assert.That(flag);
+    }
+
+    [Test]
+    public void DeletePosition_RecordWithIncorrectId_ThrowException_Test()
+    {
+        //Arrange
+        var id = Guid.NewGuid().ToString();
+        _positionStorageContract.Setup(x => x.DelElement(It.IsAny<string>())).Throws(new ElementNotFoundException(id));
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.DeletePosition(Guid.NewGuid().ToString()), Throws.TypeOf<ElementNotFoundException>());
+        _positionStorageContract.Verify(x => x.DelElement(It.IsAny<string>()), Times.Once);
+    }
+
+    [Test]
+    public void DeletePosition_IdIsNullOrEmpty_ThrowException_Test()
+    {
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.DeletePosition(null), Throws.TypeOf<ArgumentNullException>());
+        Assert.That(() => _positionBusinessLogicContract.DeletePosition(string.Empty), Throws.TypeOf<ArgumentNullException>());
+        _positionStorageContract.Verify(x => x.DelElement(It.IsAny<string>()), Times.Never);
+    }
+
+    [Test]
+    public void DeletePosition_IdIsNotGuid_ThrowException_Test()
+    {
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.DeletePosition("id"), Throws.TypeOf<ValidationException>());
+        _positionStorageContract.Verify(x => x.DelElement(It.IsAny<string>()), Times.Never);
+    }
+
+    [Test]
+    public void DeletePosition_StorageThrowError_ThrowException_Test()
+    {
+        //Arrange
+        _positionStorageContract.Setup(x => x.DelElement(It.IsAny<string>())).Throws(new StorageException(new InvalidOperationException()));
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.DeletePosition(Guid.NewGuid().ToString()), Throws.TypeOf<StorageException>());
+        _positionStorageContract.Verify(x => x.DelElement(It.IsAny<string>()), Times.Once);
+    }
+
+    [Test]
+    public void RestorePosition_CorrectRecord_Test()
+    {
+        //Arrange
+        var id = Guid.NewGuid().ToString();
+        var flag = false;
+        _positionStorageContract.Setup(x => x.ResElement(It.Is((string x) => x == id))).Callback(() => { flag = true; });
+        //Act
+        _positionBusinessLogicContract.RestorePosition(id);
+        //Assert
+        _positionStorageContract.Verify(x => x.ResElement(It.IsAny<string>()), Times.Once);
+        Assert.That(flag);
+    }
+
+    [Test]
+    public void RestorePosition_RecordWithIncorrectId_ThrowException_Test()
+    {
+        //Arrange
+        var id = Guid.NewGuid().ToString();
+        _positionStorageContract.Setup(x => x.ResElement(It.IsAny<string>())).Throws(new ElementNotFoundException(id));
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.RestorePosition(Guid.NewGuid().ToString()), Throws.TypeOf<ElementNotFoundException>());
+        _positionStorageContract.Verify(x => x.ResElement(It.IsAny<string>()), Times.Once);
+    }
+
+    [Test]
+    public void RestorePosition_IdIsNullOrEmpty_ThrowException_Test()
+    {
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.RestorePosition(null), Throws.TypeOf<ArgumentNullException>());
+        Assert.That(() => _positionBusinessLogicContract.RestorePosition(string.Empty), Throws.TypeOf<ArgumentNullException>());
+        _positionStorageContract.Verify(x => x.ResElement(It.IsAny<string>()), Times.Never);
+    }
+
+    [Test]
+    public void RestorePosition_IdIsNotGuid_ThrowException_Test()
+    {
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.RestorePosition("id"), Throws.TypeOf<ValidationException>());
+        _positionStorageContract.Verify(x => x.ResElement(It.IsAny<string>()), Times.Never);
+    }
+
+    [Test]
+    public void RestorePosition_StorageThrowError_ThrowException_Test()
+    {
+        //Arrange
+        _positionStorageContract.Setup(x => x.ResElement(It.IsAny<string>())).Throws(new StorageException(new InvalidOperationException()));
+        //Act&Assert
+        Assert.That(() => _positionBusinessLogicContract.RestorePosition(Guid.NewGuid().ToString()), Throws.TypeOf<StorageException>());
+        _positionStorageContract.Verify(x => x.ResElement(It.IsAny<string>()), Times.Once);
+    }
+}

AndDietCokeProject/AndDietCokeTests/BusinessLogicsContractsTests/SalaryBusinessLogicsContractsTests.cs

@@ -0,0 +1,144 @@
+using AndDietCokeContracts.BusinessLogicsContracts;
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.Extensions;
+using AndDietCokeContracts.StorageContract;
+using Microsoft.Extensions.Logging;
+using Moq;
+
+namespace AndDietCokeTests.BusinessLogicsContractsTests;
+
+[TestFixture]
+internal class SalaryBusinessLogicsContractsTests
+{
+    private SalaryBusinessLogicContract _salaryBusinessLogicContract;
+    private Mock<ISalaryStorageContract> _salaryStorageContract;
+    private Mock<ILogger> _logger;
+
+    [OneTimeSetUp]
+    public void OneTimeSetUp()
+    {
+        _salaryStorageContract = new Mock<ISalaryStorageContract>();
+        _logger = new Mock<ILogger>();
+        _salaryBusinessLogicContract = new SalaryBusinessLogicContract(
+            _salaryStorageContract.Object,
+            _logger.Object);
+    }
+
+    [SetUp]
+    public void SetUp()
+    {
+        _salaryStorageContract.Reset();
+        _logger.Reset();
+    }
+
+    [Test]
+    public void GetAllSalariesByPeriod_ReturnListOfRecords_Test()
+    {
+        // Arrange
+        var startDate = DateTime.UtcNow;
+        var endDate = DateTime.UtcNow.AddDays(1);
+        var listOriginal = new List<SalaryDataModel>()
+        {
+            new(Guid.NewGuid().ToString(), DateTime.UtcNow, 1000, Guid.NewGuid().ToString()),
+            new(Guid.NewGuid().ToString(), DateTime.UtcNow.AddDays(1), 1500, Guid.NewGuid().ToString()),
+            new(Guid.NewGuid().ToString(), DateTime.UtcNow.AddDays(-1), 800, Guid.NewGuid().ToString()),
+        };
+
+        _salaryStorageContract.Setup(x => x.GetList(It.IsAny<DateTime>(), It.IsAny<DateTime>(), null))
+            .Returns(listOriginal);
+
+        // Act
+        var result = _salaryBusinessLogicContract.GetAllSalariesByPeriod(startDate, endDate);
+
+        // Assert
+        Assert.That(result, Is.Not.Null);
+        Assert.That(result, Is.EquivalentTo(listOriginal));
+        _salaryStorageContract.Verify(x => x.GetList(startDate, endDate, null), Times.Once);
+    }
+
+    [Test]
+    public void GetAllSalariesByPeriod_IncorrectDates_ThrowException_Test()
+    {
+        // Arrange
+        var dateTime = DateTime.UtcNow;
+
+        // Act & Assert
+        Assert.That(() => _salaryBusinessLogicContract.GetAllSalariesByPeriod(dateTime, dateTime),
+            Throws.TypeOf<IncorrectDatesException>());
+        Assert.That(() => _salaryBusinessLogicContract.GetAllSalariesByPeriod(dateTime, dateTime.AddSeconds(-1)),
+            Throws.TypeOf<IncorrectDatesException>());
+
+        _salaryStorageContract.Verify(x => x.GetList(It.IsAny<DateTime>(), It.IsAny<DateTime>(), It.IsAny<string>()), Times.Never);
+    }
+
+    [Test]
+    public void GetAllSalariesByPeriod_ReturnNull_ThrowException_Test()
+    {
+        // Arrange
+        _salaryStorageContract.Setup(x => x.GetList(It.IsAny<DateTime>(), It.IsAny<DateTime>(), null))
+            .Returns((List<SalaryDataModel>)null);
+
+        // Act & Assert
+        Assert.That(() => _salaryBusinessLogicContract.GetAllSalariesByPeriod(DateTime.UtcNow, DateTime.UtcNow.AddDays(1)),
+            Throws.TypeOf<NullListException>());
+    }
+
+    [Test]
+    public void GetAllSalariesByPeriod_StorageThrowError_ThrowException_Test()
+    {
+        // Arrange
+        _salaryStorageContract.Setup(x => x.GetList(It.IsAny<DateTime>(), It.IsAny<DateTime>(), null))
+            .Throws(new StorageException(new InvalidOperationException()));
+
+        // Act & Assert
+        Assert.That(() => _salaryBusinessLogicContract.GetAllSalariesByPeriod(DateTime.UtcNow, DateTime.UtcNow.AddDays(1)),
+            Throws.TypeOf<StorageException>());
+    }
+
+    [Test]
+    public void GetAllSalariesByPeriodByEmployee_ReturnListOfRecords_Test()
+    {
+        // Arrange
+        var startDate = DateTime.UtcNow;
+        var endDate = DateTime.UtcNow.AddDays(1);
+        var employeeId = Guid.NewGuid().ToString();
+        var listOriginal = new List<SalaryDataModel>()
+        {
+            new(Guid.NewGuid().ToString(), DateTime.UtcNow, 1000, employeeId),
+            new(Guid.NewGuid().ToString(), DateTime.UtcNow.AddDays(1), 1500, employeeId),
+        };
+
+        _salaryStorageContract.Setup(x => x.GetList(It.IsAny<DateTime>(), It.IsAny<DateTime>(), employeeId))
+            .Returns(listOriginal);
+
+        // Act
+        var result = _salaryBusinessLogicContract.GetAllSalariesByPeriodByEmployee(startDate, endDate, employeeId);
+
+        // Assert
+        Assert.That(result, Is.Not.Null);
+        Assert.That(result, Is.EquivalentTo(listOriginal));
+        _salaryStorageContract.Verify(x => x.GetList(startDate, endDate, employeeId), Times.Once);
+    }
+
+    [Test]
+    public void GetAllSalariesByPeriodByEmployee_EmployeeIdIsNullOrEmpty_ThrowException_Test()
+    {
+        // Act & Assert
+        Assert.That(() => _salaryBusinessLogicContract.GetAllSalariesByPeriodByEmployee(DateTime.UtcNow, DateTime.UtcNow.AddDays(1), null),
+            Throws.TypeOf<ArgumentNullException>());
+        Assert.That(() => _salaryBusinessLogicContract.GetAllSalariesByPeriodByEmployee(DateTime.UtcNow, DateTime.UtcNow.AddDays(1), string.Empty),
+            Throws.TypeOf<ArgumentNullException>());
+
+        _salaryStorageContract.Verify(x => x.GetList(It.IsAny<DateTime>(), It.IsAny<DateTime>(), It.IsAny<string>()), Times.Never);
+    }
+
+    [Test]
+    public void GetAllSalariesByPeriodByEmployee_EmployeeIdIsNotGuid_ThrowException_Test()
+    {
+        // Act & Assert
+        Assert.That(() => _salaryBusinessLogicContract.GetAllSalariesByPeriodByEmployee(DateTime.UtcNow, DateTime.UtcNow.AddDays(1), "invalid-id"),
+            Throws.TypeOf<ValidationException>());
+    }
+
+}

AndDietCokeProject/AndDietCokeTests/BusinessLogicsContractsTests/СlientBusinessLogicsContractsTests.cs

@@ -0,0 +1,289 @@
+using AndDietCokeBusinessLogic.Implementations;
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeContracts.StoragesContracts;
+using Microsoft.Extensions.Logging;
+using Moq;
+
+namespace AndDietCokeTests.BusinessLogicsContractsTests;
+
+[TestFixture]
+internal class СlientBusinessLogicsContractsTests
+{
+    private ClientBusinessLogicContract _clientLogicContract;
+    private Mock<IClientStorageContract> _clientStorageContract;
+
+    [OneTimeSetUp]
+    public void OneTimeSetUp()
+    {
+        _clientStorageContract = new Mock<IClientStorageContract>();
+        _clientLogicContract = new ClientBusinessLogicContract(
+            _clientStorageContract.Object,
+            new Mock<ILogger>().Object);
+    }
+
+    [SetUp]
+    public void SetUp()
+    {
+        _clientStorageContract.Reset();
+    }
+
+    // GetAllClients tests
+    [Test]
+    public void GetAllClients_ReturnListOfRecords_Test()
+    {
+        // Arrange
+        var listOriginal = new List<СlientDataModel>()
+        {
+            new(Guid.NewGuid().ToString(), "Client 1", "+7-111-111-11-11", 0),
+            new(Guid.NewGuid().ToString(), "Client 2", "+7-222-222-22-22", 5),
+        };
+
+        _clientStorageContract.Setup(x => x.GetList()).Returns(listOriginal);
+
+        // Act
+        var list = _clientLogicContract.GetAllClients();
+
+        // Assert
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Is.EquivalentTo(listOriginal));
+        _clientStorageContract.Verify(x => x.GetList(), Times.Once);
+    }
+
+    [Test]
+    public void GetAllClients_ReturnEmptyList_Test()
+    {
+        // Arrange
+        _clientStorageContract.Setup(x => x.GetList()).Returns([]);
+
+        // Act
+        var list = _clientLogicContract.GetAllClients();
+
+        // Assert
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(0));
+        _clientStorageContract.Verify(x => x.GetList(), Times.Once);
+    }
+
+    [Test]
+    public void GetAllClients_ReturnNull_ThrowException_Test()
+    {
+        // Arrange
+        _clientStorageContract.Setup(x => x.GetList()).Returns(null as List<СlientDataModel>);
+
+        // Act & Assert
+        Assert.That(() => _clientLogicContract.GetAllClients(),
+            Throws.TypeOf<NullListException>());
+        _clientStorageContract.Verify(x => x.GetList(), Times.Once);
+    }
+
+    [Test]
+    public void GetAllClients_StorageThrowError_ThrowException_Test()
+    {
+        // Arrange
+        _clientStorageContract.Setup(x => x.GetList())
+            .Throws(new StorageException(new InvalidOperationException()));
+
+        // Act & Assert
+        Assert.That(() => _clientLogicContract.GetAllClients(),
+            Throws.TypeOf<StorageException>());
+        _clientStorageContract.Verify(x => x.GetList(), Times.Once);
+    }
+
+    // GetClientByData tests
+    [Test]
+    public void GetClientByData_GetById_ReturnRecord_Test()
+    {
+        // Arrange
+        var id = Guid.NewGuid().ToString();
+        var record = new СlientDataModel(id, "Client", "+7-111-111-11-11", 0);
+        _clientStorageContract.Setup(x => x.GetElementById(id)).Returns(record);
+
+        // Act
+        var element = _clientLogicContract.GetClientByData(id);
+
+        // Assert
+        Assert.That(element, Is.Not.Null);
+        Assert.That(element.Id, Is.EqualTo(id));
+        _clientStorageContract.Verify(x => x.GetElementById(id), Times.Once);
+        _clientStorageContract.Verify(x => x.GetElementByFIO(It.IsAny<string>()), Times.Never);
+        _clientStorageContract.Verify(x => x.GetElementByPhoneNumber(It.IsAny<string>()), Times.Never);
+    }
+
+    [Test]
+    public void GetClientByData_GetByFio_ReturnRecord_Test()
+    {
+        // Arrange
+        var fio = "Client Name";
+        var record = new СlientDataModel(Guid.NewGuid().ToString(), fio, "+7-111-111-11-11", 0);
+        _clientStorageContract.Setup(x => x.GetElementByFIO(fio)).Returns(record);
+
+        // Act
+        var element = _clientLogicContract.GetClientByData(fio);
+
+        // Assert
+        Assert.That(element, Is.Not.Null);
+        Assert.That(element.FIO, Is.EqualTo(fio));
+        _clientStorageContract.Verify(x => x.GetElementByFIO(fio), Times.Once);
+        _clientStorageContract.Verify(x => x.GetElementById(It.IsAny<string>()), Times.Never);
+        _clientStorageContract.Verify(x => x.GetElementByPhoneNumber(It.IsAny<string>()), Times.Never);
+    }
+
+    [Test]
+    public void GetClientByData_GetByPhoneNumber_ReturnRecord_Test()
+    {
+        // Arrange
+        var phone = "+7-111-111-11-11";
+        var record = new СlientDataModel(Guid.NewGuid().ToString(), "Client", phone, 0);
+        _clientStorageContract.Setup(x => x.GetElementByPhoneNumber(phone)).Returns(record);
+
+        // Act
+        var element = _clientLogicContract.GetClientByData(phone);
+
+        // Assert
+        Assert.That(element, Is.Not.Null);
+        Assert.That(element.Contact, Is.EqualTo(phone));
+        _clientStorageContract.Verify(x => x.GetElementByPhoneNumber(phone), Times.Once);
+        _clientStorageContract.Verify(x => x.GetElementById(It.IsAny<string>()), Times.Never);
+        _clientStorageContract.Verify(x => x.GetElementByFIO(It.IsAny<string>()), Times.Never);
+    }
+
+    [Test]
+    public void GetClientByData_EmptyData_ThrowException_Test()
+    {
+        // Act & Assert
+        Assert.That(() => _clientLogicContract.GetClientByData(null),
+            Throws.TypeOf<ArgumentNullException>());
+        Assert.That(() => _clientLogicContract.GetClientByData(string.Empty),
+            Throws.TypeOf<ArgumentNullException>());
+        _clientStorageContract.Verify(x => x.GetElementById(It.IsAny<string>()), Times.Never);
+        _clientStorageContract.Verify(x => x.GetElementByPhoneNumber(It.IsAny<string>()), Times.Never);
+        _clientStorageContract.Verify(x => x.GetElementByFIO(It.IsAny<string>()), Times.Never);
+    }
+
+    [Test]
+    public void GetClientByData_NotFound_ThrowException_Test()
+    {
+        // Arrange
+        var testData = Guid.NewGuid().ToString();
+        _clientStorageContract.Setup(x => x.GetElementById(testData)).Returns(null as СlientDataModel);
+        _clientStorageContract.Setup(x => x.GetElementByFIO(testData)).Returns(null as СlientDataModel);
+        _clientStorageContract.Setup(x => x.GetElementByPhoneNumber(testData)).Returns(null as СlientDataModel);
+
+        // Act & Assert
+        Assert.That(() => _clientLogicContract.GetClientByData(testData),
+            Throws.TypeOf<ElementNotFoundException>());
+    }
+
+    // InsertClient tests
+    [Test]
+    public void InsertClient_CorrectRecord_Test()
+    {
+        // Arrange
+        var record = new СlientDataModel(Guid.NewGuid().ToString(), "Client", "+7-111-111-11-11", 0);
+        _clientStorageContract.Setup(x => x.AddElement(It.IsAny<СlientDataModel>()));
+
+        // Act
+        _clientLogicContract.InsertClient(record);
+
+        // Assert
+        _clientStorageContract.Verify(x => x.AddElement(record), Times.Once);
+    }
+
+    [Test]
+    public void InsertClient_NullRecord_ThrowException_Test()
+    {
+        // Act & Assert
+        Assert.That(() => _clientLogicContract.InsertClient(null),
+            Throws.TypeOf<ArgumentNullException>());
+        _clientStorageContract.Verify(x => x.AddElement(It.IsAny<СlientDataModel>()), Times.Never);
+    }
+
+    [Test]
+    public void InsertClient_InvalidRecord_ThrowException_Test()
+    {
+        // Act & Assert
+        Assert.That(() => _clientLogicContract.InsertClient(
+            new СlientDataModel("invalid-id", "Client", "invalid-phone", 0)),
+            Throws.TypeOf<ValidationException>());
+        _clientStorageContract.Verify(x => x.AddElement(It.IsAny<СlientDataModel>()), Times.Never);
+    }
+
+    [Test]
+    public void InsertClient_DuplicateData_ThrowException_Test()
+    {
+        // Arrange
+        var record = new СlientDataModel(Guid.NewGuid().ToString(), "Client", "+7-111-111-11-11", 0);
+        _clientStorageContract.Setup(x => x.AddElement(record))
+            .Throws(new ElementExistsException("Client", "already exists"));
+
+        // Act & Assert
+        Assert.That(() => _clientLogicContract.InsertClient(record),
+            Throws.TypeOf<ElementExistsException>());
+    }
+
+    // UpdateClient tests
+    [Test]
+    public void UpdateClient_CorrectRecord_Test()
+    {
+        // Arrange
+        var record = new СlientDataModel(Guid.NewGuid().ToString(), "Client", "+7-111-111-11-11", 0);
+        _clientStorageContract.Setup(x => x.UpdElement(It.IsAny<СlientDataModel>()));
+
+        // Act
+        _clientLogicContract.UpdateClient(record);
+
+        // Assert
+        _clientStorageContract.Verify(x => x.UpdElement(record), Times.Once);
+    }
+
+    [Test]
+    public void UpdateClient_NotFound_ThrowException_Test()
+    {
+        // Arrange
+        var record = new СlientDataModel(Guid.NewGuid().ToString(), "Client", "+7-111-111-11-11", 0);
+        _clientStorageContract.Setup(x => x.UpdElement(record))
+            .Throws(new ElementNotFoundException("Client not found"));
+
+        // Act & Assert
+        Assert.That(() => _clientLogicContract.UpdateClient(record),
+            Throws.TypeOf<ElementNotFoundException>());
+    }
+
+    // DeleteClient tests
+    [Test]
+    public void DeleteClient_CorrectId_Test()
+    {
+        // Arrange
+        var id = Guid.NewGuid().ToString();
+        _clientStorageContract.Setup(x => x.DelElement(id));
+
+        // Act
+        _clientLogicContract.DeleteClient(id);
+
+        // Assert
+        _clientStorageContract.Verify(x => x.DelElement(id), Times.Once);
+    }
+
+    [Test]
+    public void DeleteClient_NotFound_ThrowException_Test()
+    {
+        // Arrange
+        var id = Guid.NewGuid().ToString();
+        _clientStorageContract.Setup(x => x.DelElement(id))
+            .Throws(new ElementNotFoundException("Client not found"));
+
+        // Act & Assert
+        Assert.That(() => _clientLogicContract.DeleteClient(id),
+            Throws.TypeOf<ElementNotFoundException>());
+    }
+
+    [Test]
+    public void DeleteClient_InvalidId_ThrowException_Test()
+    {
+        // Act & Assert
+        Assert.That(() => _clientLogicContract.DeleteClient("not-a-guid"),
+            Throws.TypeOf<ValidationException>());
+        _clientStorageContract.Verify(x => x.DelElement(It.IsAny<string>()), Times.Never);
+    }
+}

AndDietCokeProject/AndDietCokeTests/DataModelsTests/PositionDataModelTests.cs

@@ -1,8 +1,6 @@
 using AndDietCokeContracts.DataModels;
 using AndDietCokeContracts.Enums;
 using AndDietCokeContracts.Exceptions;
-using NUnit.Framework;
-using System;
 
 namespace AndDietCokeTests.DataModelsTests
 {
@@ -12,91 +10,67 @@ namespace AndDietCokeTests.DataModelsTests
         [Test]
         public void IdIsNullOrEmptyTest()
         {
-            var position = CreateDataModel(null, Guid.NewGuid().ToString(), "name", PositionType.Assistant, 10, true, DateTime.UtcNow);
-            Assert.That(() => position.Validate(), Throws.TypeOf<ValidationException>());
-
-            position = CreateDataModel(string.Empty, Guid.NewGuid().ToString(), "name", PositionType.Assistant, 10, true, DateTime.UtcNow);
-            Assert.That(() => position.Validate(), Throws.TypeOf<ValidationException>());
+            var post = CreateDataModel(null, "name", PositionType.Assistant, 10, true, DateTime.UtcNow);
+            Assert.That(() => post.Validate(), Throws.TypeOf<ValidationException>());
+            post = CreateDataModel(string.Empty, "name", PositionType.Assistant, 10, true, DateTime.UtcNow);
+            Assert.That(() => post.Validate(), Throws.TypeOf<ValidationException>());
         }
 
         [Test]
         public void IdIsNotGuidTest()
         {
-            var position = CreateDataModel("id", Guid.NewGuid().ToString(), "name", PositionType.Assistant, 10, true, DateTime.UtcNow);
-            Assert.That(() => position.Validate(), Throws.TypeOf<ValidationException>());
+            var post = CreateDataModel("id", "name", PositionType.Assistant, 10, true, DateTime.UtcNow);
+            Assert.That(() => post.Validate(), Throws.TypeOf<ValidationException>());
         }
 
         [Test]
-        public void PositionIdIsNullOrEmptyTest()
+        public void PostNameIsEmptyTest()
         {
-            var position = CreateDataModel(Guid.NewGuid().ToString(), null, "name", PositionType.Assistant, 10, true, DateTime.UtcNow);
-            Assert.That(() => position.Validate(), Throws.TypeOf<ValidationException>());
-
-            position = CreateDataModel(Guid.NewGuid().ToString(), string.Empty, "name", PositionType.Assistant, 10, true, DateTime.UtcNow);
-            Assert.That(() => position.Validate(), Throws.TypeOf<ValidationException>());
-        }
-
-        [Test]
-        public void PositionIdIsNotGuidTest()
-        {
-            var position = CreateDataModel(Guid.NewGuid().ToString(), "positionId", "name", PositionType.Assistant, 10, true, DateTime.UtcNow);
-            Assert.That(() => position.Validate(), Throws.TypeOf<ValidationException>());
-        }
-
-        [Test]
-        public void PositionNameIsEmptyTest()
-        {
-            var position = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), null, PositionType.Assistant, 10, true, DateTime.UtcNow);
-            Assert.That(() => position.Validate(), Throws.TypeOf<ValidationException>());
-
-            position = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), string.Empty, PositionType.Assistant, 10, true, DateTime.UtcNow);
-            Assert.That(() => position.Validate(), Throws.TypeOf<ValidationException>());
+            var manufacturer = CreateDataModel(Guid.NewGuid().ToString(), null, PositionType.Assistant, 10, true, DateTime.UtcNow);
+            Assert.That(() => manufacturer.Validate(), Throws.TypeOf<ValidationException>());
+            manufacturer = CreateDataModel(Guid.NewGuid().ToString(), string.Empty, PositionType.Assistant, 10, true, DateTime.UtcNow);
+            Assert.That(() => manufacturer.Validate(), Throws.TypeOf<ValidationException>());
         }
 
         [Test]
         public void PositionTypeIsNoneTest()
         {
-            var position = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), "name", PositionType.None, 10, true, DateTime.UtcNow);
-            Assert.That(() => position.Validate(), Throws.TypeOf<ValidationException>());
+            var post = CreateDataModel(Guid.NewGuid().ToString(), "name", PositionType.None, 10, true, DateTime.UtcNow);
+            Assert.That(() => post.Validate(), Throws.TypeOf<ValidationException>());
         }
 
         [Test]
         public void SalaryIsLessOrZeroTest()
         {
-            var position = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), "name", PositionType.Assistant, 0, true, DateTime.UtcNow);
-            Assert.That(() => position.Validate(), Throws.TypeOf<ValidationException>());
-
-            position = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), "name", PositionType.Assistant, -10, true, DateTime.UtcNow);
-            Assert.That(() => position.Validate(), Throws.TypeOf<ValidationException>());
+            var post = CreateDataModel(Guid.NewGuid().ToString(), "name", PositionType.Assistant, 0, true, DateTime.UtcNow);
+            Assert.That(() => post.Validate(), Throws.TypeOf<ValidationException>());
+            post = CreateDataModel(Guid.NewGuid().ToString(), "name", PositionType.Assistant, -10, true, DateTime.UtcNow);
+            Assert.That(() => post.Validate(), Throws.TypeOf<ValidationException>());
         }
 
         [Test]
-        public void AllFieldsAreCorrectTest()
+        public void AllFieldsIsCorrectTest()
         {
-            var id = Guid.NewGuid().ToString();
-            var positionId = Guid.NewGuid().ToString();
-            var positionName = "name";
+            var postId = Guid.NewGuid().ToString();
+            var postName = "name";
             var positionType = PositionType.Assistant;
             var salary = 10;
             var isActual = false;
             var changeDate = DateTime.UtcNow.AddDays(-1);
-
-            var position = CreateDataModel(id, positionId, positionName, positionType, salary, isActual, changeDate);
-
-            Assert.That(() => position.Validate(), Throws.Nothing);
+            var post = CreateDataModel(postId, postName, positionType, salary, isActual, changeDate);
+            Assert.That(() => post.Validate(), Throws.Nothing);
             Assert.Multiple(() =>
             {
-                Assert.That(position.Id, Is.EqualTo(id));
-                Assert.That(position.PositionId, Is.EqualTo(positionId));
-                Assert.That(position.PositionName, Is.EqualTo(positionName));
-                Assert.That(position.PositionType, Is.EqualTo(positionType));
-                Assert.That(position.Salary, Is.EqualTo(salary));
-                Assert.That(position.IsActual, Is.EqualTo(isActual));
-                Assert.That(position.ChangeDate, Is.EqualTo(changeDate));
+                Assert.That(post.Id, Is.EqualTo(postId));
+                Assert.That(post.PositionName, Is.EqualTo(postName));
+                Assert.That(post.PositionType, Is.EqualTo(positionType));
+                Assert.That(post.Salary, Is.EqualTo(salary));
+                Assert.That(post.IsActual, Is.EqualTo(isActual));
+                Assert.That(post.ChangeDate, Is.EqualTo(changeDate));
             });
         }
 
-        private static PositionDataModell CreateDataModel(string? id, string? positionId, string? positionName, PositionType positionType, double salary, bool isActual, DateTime changeDate) =>
-            new(id, positionId, positionName, positionType, salary, isActual, changeDate);
+        private static PositionDataModel CreateDataModel(string? id, string? postName, PositionType positionType, double salary, bool isActual, DateTime changeDate) =>
+            new(id, postName, positionType, salary, isActual, changeDate);
     }
 }

AndDietCokeProject/AndDietCokeTests/Infrastucture/ConfigurationDatabaseTest.cs

@@ -0,0 +1,9 @@
+using AndDietCokeContracts.Infrastructure;
+
+namespace AndDietCokeTests.Infrastucture;
+
+internal class ConfigurationDatabaseTest : IConfigurationDatabase
+{
+    public string ConnectionString => "Host=127.0.0.1;Port=5432;Database=AndDietCokeTest;Username=postgres;Password=postgres;";
+}
+

AndDietCokeProject/AndDietCokeTests/StorageContractTests/BaseStorageContractTest.cs

@@ -0,0 +1,25 @@
+using AndDietCokeDatabase;
+using AndDietCokeTests.Infrastucture;
+
+namespace AndDietCokeTests.StorageContractTests;
+
+internal abstract class BaseStorageContractTest
+{
+    protected AndDietCokeDbContext AndDietCokeDbContext { get; private set; }
+
+    [OneTimeSetUp]
+    public void OneTimeSetUp()
+    {
+        AndDietCokeDbContext = new AndDietCokeDbContext(new ConfigurationDatabaseTest());
+
+        AndDietCokeDbContext.Database.EnsureDeleted();
+        AndDietCokeDbContext.Database.EnsureCreated();
+    }
+
+    [OneTimeTearDown]
+    public void OneTimeTearDown()
+    {
+        AndDietCokeDbContext.Database.EnsureDeleted();
+        AndDietCokeDbContext.Dispose();
+    }
+}

AndDietCokeProject/AndDietCokeTests/StorageContractTests/ClientStorageContractTests.cs

@@ -0,0 +1,212 @@
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Enums;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeDatabase.Implementations;
+using AndDietCokeDatabase.Models;
+using Microsoft.EntityFrameworkCore;
+
+namespace AndDietCokeTests.StorageContractTests;
+
+[TestFixture]
+internal class ClientStorageContractTests : BaseStorageContractTest
+{
+    private ClientStorageContract _clientStorageContract;
+
+    [SetUp]
+    public void SetUp()
+    {
+        _clientStorageContract = new ClientStorageContract(AndDietCokeDbContext);
+    }
+
+    [TearDown]
+    public void TearDown()
+    {
+        AndDietCokeDbContext.Database.ExecuteSqlRaw("TRUNCATE \"Orders\" CASCADE;");
+        AndDietCokeDbContext.Database.ExecuteSqlRaw("TRUNCATE \"Employees\" CASCADE;");
+        AndDietCokeDbContext.Database.ExecuteSqlRaw("TRUNCATE \"Clients\" CASCADE;");
+    }
+
+    [Test]
+    public void Try_GetList_WhenHaveRecords_Test()
+    {
+        var client = InsertClientToDatabaseAndReturn(Guid.NewGuid().ToString(), contact: "+5-555-555-55-55");
+        InsertClientToDatabaseAndReturn(Guid.NewGuid().ToString(), contact: "+6-666-666-66-66");
+        InsertClientToDatabaseAndReturn(Guid.NewGuid().ToString(), contact: "+7-777-777-77-77");
+        var list = _clientStorageContract.GetList();
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(3));
+        AssertElement(list.First(x => x.Id == client.Id), client);
+    }
+
+    [Test]
+    public void Try_GetList_WhenNoRecords_Test()
+    {
+        var list = _clientStorageContract.GetList();
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Is.Empty);
+    }
+
+    [Test]
+    public void Try_GetElementById_WhenHaveRecord_Test()
+    {
+        var client = InsertClientToDatabaseAndReturn(Guid.NewGuid().ToString());
+        AssertElement(_clientStorageContract.GetElementById(client.Id), client);
+    }
+
+    [Test]
+    public void Try_GetElementById_WhenNoRecord_Test()
+    {
+        InsertClientToDatabaseAndReturn(Guid.NewGuid().ToString());
+        Assert.That(() => _clientStorageContract.GetElementById(Guid.NewGuid().ToString()), Is.Null);
+    }
+
+    [Test]
+    public void Try_GetElementByFIO_WhenHaveRecord_Test()
+    {
+        var client = InsertClientToDatabaseAndReturn(Guid.NewGuid().ToString());
+        AssertElement(_clientStorageContract.GetElementByFIO(client.FIO), client);
+    }
+
+    [Test]
+    public void Try_GetElementByFIO_WhenNoRecord_Test()
+    {
+        InsertClientToDatabaseAndReturn(Guid.NewGuid().ToString());
+        Assert.That(() => _clientStorageContract.GetElementByFIO("New Fio"), Is.Null);
+    }
+
+    [Test]
+    public void Try_GetElementByPhoneNumber_WhenHaveRecord_Test()
+    {
+        var client = InsertClientToDatabaseAndReturn(Guid.NewGuid().ToString());
+        AssertElement(_clientStorageContract.GetElementByPhoneNumber(client.Contact), client);
+    }
+
+    [Test]
+    public void Try_GetElementByPhoneNumber_WhenNoRecord_Test()
+    {
+        InsertClientToDatabaseAndReturn(Guid.NewGuid().ToString());
+        Assert.That(() => _clientStorageContract.GetElementByPhoneNumber("+8-888-888-88-88"), Is.Null);
+    }
+
+    [Test]
+    public void Try_AddElement_Test()
+    {
+        var client = CreateModel(Guid.NewGuid().ToString());
+        _clientStorageContract.AddElement(client);
+        AssertElement(GetClientFromDatabase(client.Id), client);
+    }
+
+    [Test]
+    public void Try_AddElement_WhenHaveRecordWithSameId_Test()
+    {
+        var client = CreateModel(Guid.NewGuid().ToString(), "New Fio", "+5-555-555-55-55", 500);
+        InsertClientToDatabaseAndReturn(client.Id);
+        Assert.That(() => _clientStorageContract.AddElement(client), Throws.TypeOf<ElementExistsException>());
+    }
+
+    [Test]
+    public void Try_AddElement_WhenHaveRecordWithSamePhoneNumber_Test()
+    {
+        var client = CreateModel(Guid.NewGuid().ToString(), "New Fio", "+5-555-555-55-55", 500);
+        InsertClientToDatabaseAndReturn(Guid.NewGuid().ToString(), contact: client.Contact);
+        Assert.That(() => _clientStorageContract.AddElement(client), Throws.TypeOf<ElementExistsException>());
+    }
+
+    [Test]
+    public void Try_UpdElement_Test()
+    {
+        var client = CreateModel(Guid.NewGuid().ToString(), "New Fio", "+5-555-555-55-55", 500);
+        InsertClientToDatabaseAndReturn(client.Id);
+        _clientStorageContract.UpdElement(client);
+        AssertElement(GetClientFromDatabase(client.Id), client);
+    }
+
+    [Test]
+    public void Try_UpdElement_WhenNoRecordWithThisId_Test()
+    {
+        Assert.That(() => _clientStorageContract.UpdElement(CreateModel(Guid.NewGuid().ToString())), Throws.TypeOf<ElementNotFoundException>());
+    }
+
+    [Test]
+    public void Try_UpdElement_WhenHaveRecordWithSamePhoneNumber_Test()
+    {
+        var client = CreateModel(Guid.NewGuid().ToString(), "New Fio", "+5-555-555-55-55", 500);
+        InsertClientToDatabaseAndReturn(client.Id, contact: "+7-777-777-77-77");
+        InsertClientToDatabaseAndReturn(Guid.NewGuid().ToString(), contact: client.Contact);
+        Assert.That(() => _clientStorageContract.UpdElement(client), Throws.TypeOf<ElementExistsException>());
+    }
+
+    [Test]
+    public void Try_DelElement_Test()
+    {
+        var client = InsertClientToDatabaseAndReturn(Guid.NewGuid().ToString());
+        _clientStorageContract.DelElement(client.Id);
+        var element = GetClientFromDatabase(client.Id);
+        Assert.That(element, Is.Null);
+    }
+
+    [Test]
+    public void Try_DelElement_WhenHaveSalesByThisBuyer_Test()
+    {
+        var client = InsertClientToDatabaseAndReturn(Guid.NewGuid().ToString());
+        var workerId = Guid.NewGuid().ToString();
+        AndDietCokeDbContext.Employees.Add(new Employee() { Id = workerId, FIO = "test", PositionId = Guid.NewGuid().ToString() });
+        AndDietCokeDbContext.Orders.Add(new Order() { Id = Guid.NewGuid().ToString(), EmloyeedId = workerId, ClientId = client.Id });
+        AndDietCokeDbContext.Orders.Add(new Order() { Id = Guid.NewGuid().ToString(), EmloyeedId = workerId, ClientId = client.Id });
+        AndDietCokeDbContext.SaveChanges();
+        var ordersBeforeDelete = AndDietCokeDbContext.Orders.Where(x => x.ClientId == client.Id).ToArray();
+        _clientStorageContract.DelElement(client.Id);
+        var element = GetClientFromDatabase(client.Id);
+        var salesAfterDelete = AndDietCokeDbContext.Orders.Where(x => x.ClientId == client.Id).ToArray();
+        Assert.Multiple(() =>
+        {
+            Assert.That(element, Is.Null);
+            Assert.That(ordersBeforeDelete, Has.Length.EqualTo(2));
+            Assert.That(salesAfterDelete, Is.Empty);
+            Assert.That(AndDietCokeDbContext.Orders.Count(), Is.EqualTo(2));
+        });
+    }
+
+    [Test]
+    public void Try_DelElement_WhenNoRecordWithThisId_Test()
+    {
+        Assert.That(() => _clientStorageContract.DelElement(Guid.NewGuid().ToString()), Throws.TypeOf<ElementNotFoundException>());
+    }
+
+    private Client InsertClientToDatabaseAndReturn(string id, string fio = "test", string contact = "+7-777-777-77-77", double discountSize = 10)
+    {
+        var buyer = new Client() { Id = id, FIO = fio, Contact = contact, DiscountSize = discountSize };
+        AndDietCokeDbContext.Clients.Add(buyer);
+        AndDietCokeDbContext.SaveChanges();
+        return buyer;
+    }
+
+    private static void AssertElement(СlientDataModel? actual, Client expected)
+    {
+        Assert.That(actual, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(actual.Id, Is.EqualTo(expected.Id));
+            Assert.That(actual.FIO, Is.EqualTo(expected.FIO));
+            Assert.That(actual.Contact, Is.EqualTo(expected.Contact));
+            Assert.That(actual.DiscountSize, Is.EqualTo(expected.DiscountSize));
+        });
+    }
+
+    private static СlientDataModel CreateModel(string id, string fio = "test", string contact = "+7-777-777-77-77", double discountSize = 10)
+        => new(id, fio, contact, discountSize);
+
+    private Client? GetClientFromDatabase(string id) => AndDietCokeDbContext.Clients.FirstOrDefault(x => x.Id == id);
+
+    private static void AssertElement(Client? actual, СlientDataModel expected)
+    {
+        Assert.That(actual, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(actual.Id, Is.EqualTo(expected.Id));
+            Assert.That(actual.FIO, Is.EqualTo(expected.FIO));
+            Assert.That(actual.Contact, Is.EqualTo(expected.Contact));
+            Assert.That(actual.DiscountSize, Is.EqualTo(expected.DiscountSize));
+        });
+    }
+}

AndDietCokeProject/AndDietCokeTests/StorageContractTests/DishStorageContractTests.cs

@@ -0,0 +1,230 @@
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Enums;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeDatabase.Implementations;
+using AndDietCokeDatabase.Models;
+using Microsoft.EntityFrameworkCore;
+using static NUnit.Framework.Internal.OSPlatform;
+
+namespace AndDietCokeTests.StorageContractTests;
+
+[TestFixture]
+internal class DishStorageContractTests : BaseStorageContractTest
+{
+    private DishStorageContract _dishStorageContract;
+
+    [SetUp]
+    public void SetUp()
+    {
+        _dishStorageContract = new DishStorageContract(AndDietCokeDbContext);    }
+
+    [TearDown]
+    public void TearDown()
+    {
+        AndDietCokeDbContext.Database.ExecuteSqlRaw("TRUNCATE \"Dishes\" CASCADE;");
+    }
+
+    [Test]
+    public void Try_GetList_WhenHaveRecords_Test()
+    {
+        var dish = InsertDishToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 1");
+        InsertDishToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 2");
+        InsertDishToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 3");
+        var list = _dishStorageContract.GetList();
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(3));
+        AssertElement(list.First(x => x.Id == dish.Id), dish);
+    }
+
+    [Test]
+    public void Try_GetList_WhenNoRecords_Test()
+    {
+        var list = _dishStorageContract.GetList();
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Is.Empty);
+    }
+
+    [Test]
+    public void Try_GetHistoryByDishId_WhenHaveRecords_Test()
+    {
+        var dish = InsertDishToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 1");
+        InsertDishHistoryToDatabaseAndReturn(dish.Id, 20, DateTime.UtcNow.AddDays(-1));
+        InsertDishHistoryToDatabaseAndReturn(dish.Id, 30, DateTime.UtcNow.AddMinutes(-10));
+        InsertDishHistoryToDatabaseAndReturn(dish.Id, 40, DateTime.UtcNow.AddDays(1));
+        var list = _dishStorageContract.GetHistoryByProductId(dish.Id);
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(3));
+    }
+
+    [Test]
+    public void Try_GetHistoryByProductId_WhenNoRecords_Test()
+    {
+        var dish = InsertDishToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 1");
+        InsertDishHistoryToDatabaseAndReturn(dish.Id, 20, DateTime.UtcNow.AddDays(-1));
+        InsertDishHistoryToDatabaseAndReturn(dish.Id, 30, DateTime.UtcNow.AddMinutes(-10));
+        InsertDishHistoryToDatabaseAndReturn(dish.Id, 40, DateTime.UtcNow.AddDays(1));
+        var list = _dishStorageContract.GetHistoryByProductId(Guid.NewGuid().ToString());
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(0));
+    }
+
+    [Test]
+    public void Try_GetElementById_WhenHaveRecord_Test()
+    {
+        var dish = InsertDishToDatabaseAndReturn(Guid.NewGuid().ToString());
+        AssertElement(_dishStorageContract.GetElementById(dish.Id), dish);
+    }
+
+    [Test]
+    public void Try_GetElementById_WhenNoRecord_Test()
+    {
+        InsertDishToDatabaseAndReturn(Guid.NewGuid().ToString());
+        Assert.That(() => _dishStorageContract.GetElementById(Guid.NewGuid().ToString()), Is.Null);
+    }
+
+    [Test]
+    public void Try_GetElementByName_WhenHaveRecord_Test()
+    {
+        var dish = InsertDishToDatabaseAndReturn(Guid.NewGuid().ToString());
+        AssertElement(_dishStorageContract.GetElementByName(dish.Name), dish);
+    }
+
+    [Test]
+    public void Try_GetElementByName_WhenNoRecord_Test()
+    {
+        InsertDishToDatabaseAndReturn(Guid.NewGuid().ToString());
+        Assert.That(() => _dishStorageContract.GetElementByName("name"), Is.Null);
+    }
+
+    [Test]
+    public void Try_GetElementByName_WhenRecordHasDeleted_Test()
+    {
+        var dish = InsertDishToDatabaseAndReturn(Guid.NewGuid().ToString());
+        Assert.That(() => _dishStorageContract.GetElementById(dish.Name), Is.Null);
+    }
+
+    [Test]
+    public void Try_AddElement_Test()
+    {
+        var dish = CreateModel(Guid.NewGuid().ToString());
+        _dishStorageContract.AddElement(dish);
+        AssertElement(GetDishFromDatabaseById(dish.Id), dish);
+    }
+
+    [Test]
+    public void Try_AddElement_WhenIsDeletedIsTrue_Test()
+    {
+        var dish = CreateModel(Guid.NewGuid().ToString());
+        Assert.That(() => _dishStorageContract.AddElement(dish), Throws.Nothing);
+        AssertElement(GetDishFromDatabaseById(dish.Id), CreateModel(dish.Id));
+    }
+
+    [Test]
+    public void Try_AddElement_WhenHaveRecordWithSameId_Test()
+    {
+        var dish = CreateModel(Guid.NewGuid().ToString());
+        InsertDishToDatabaseAndReturn(dish.Id, name: "name unique");
+        Assert.That(() => _dishStorageContract.AddElement(dish), Throws.TypeOf<ElementExistsException>());
+    }
+
+    [Test]
+    public void Try_AddElement_WhenHaveRecordWithSameName_Test()
+    {
+        var dish = CreateModel(Guid.NewGuid().ToString(),  "name unique");
+        InsertDishToDatabaseAndReturn(Guid.NewGuid().ToString(), name: dish.Name);
+        Assert.That(() => _dishStorageContract.AddElement(dish), Throws.TypeOf<ElementExistsException>());
+    }
+
+    [Test]
+    public void Try_UpdElement_Test()
+    {
+        var dish = CreateModel(Guid.NewGuid().ToString());
+        InsertDishToDatabaseAndReturn(dish.Id);
+        _dishStorageContract.UpdElement(dish);
+        AssertElement(GetDishFromDatabaseById(dish.Id), dish);
+    }
+
+    [Test]
+    public void Try_UpdElement_WhenIsDeletedIsTrue_Test()
+    {
+        var dish = CreateModel(Guid.NewGuid().ToString());
+        InsertDishToDatabaseAndReturn(dish.Id);
+        _dishStorageContract.UpdElement(dish);
+        AssertElement(GetDishFromDatabaseById(dish.Id), CreateModel(dish.Id));
+    }
+
+    [Test]
+    public void Try_UpdElement_WhenNoRecordWithThisId_Test()
+    {
+        Assert.That(() => _dishStorageContract.UpdElement(CreateModel(Guid.NewGuid().ToString())), Throws.TypeOf<ElementNotFoundException>());
+    }
+
+    [Test]
+    public void Try_UpdElement_WhenHaveRecordWithSameName_Test()
+    {
+        var dish = CreateModel(Guid.NewGuid().ToString(), "name unique");
+        InsertDishToDatabaseAndReturn(dish.Id,  name: "name");
+        InsertDishToDatabaseAndReturn(Guid.NewGuid().ToString(), name: dish.Name);
+        Assert.That(() => _dishStorageContract.UpdElement(dish), Throws.TypeOf<ElementExistsException>());
+    }
+
+    [Test]
+    public void Try_DelElement_Test()
+    {
+        var product = InsertDishToDatabaseAndReturn(Guid.NewGuid().ToString());
+        _dishStorageContract.DelElement(product.Id);
+        var element = GetDishFromDatabaseById(product.Id);
+        Assert.That(element, Is.Null);
+    }
+
+    [Test]
+    public void Try_DelElement_WhenNoRecordWithThisId_Test()
+    {
+        Assert.That(() => _dishStorageContract.DelElement(Guid.NewGuid().ToString()), Throws.TypeOf<ElementNotFoundException>());
+    }
+
+    private Dish InsertDishToDatabaseAndReturn(string id, string name = "test", DishType dishType = DishType.Pepperoni, double price = 1, string? orderId = null)
+    {
+        var product = new Dish() { Id = id, Name = name, DishType = dishType, Price = price, OrderId = orderId ?? Guid.NewGuid().ToString() };
+        AndDietCokeDbContext.Dishes.Add(product);
+        AndDietCokeDbContext.SaveChanges();
+        return product;
+    }
+
+    private DishHistory InsertDishHistoryToDatabaseAndReturn(string dishId, double price, DateTime changeDate, string? orderId = null)
+    {
+        var productHistory = new DishHistory() { Id = Guid.NewGuid().ToString(), DishId = dishId, OldPrice = price, ChangeDate = changeDate, OrderId = orderId ?? Guid.NewGuid().ToString() };
+        AndDietCokeDbContext.DishHistories.Add(productHistory);
+        AndDietCokeDbContext.SaveChanges();
+        return productHistory;
+    }
+
+    private static void AssertElement(DishDataModel? actual, Dish expected)
+    {
+        Assert.That(actual, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(actual.Id, Is.EqualTo(expected.Id));
+            Assert.That(actual.Name, Is.EqualTo(expected.Name));
+            Assert.That(actual.DishType, Is.EqualTo(expected.DishType));
+            Assert.That(actual.Price, Is.EqualTo(expected.Price));
+        });
+    }
+
+    private static DishDataModel CreateModel(string id, string name = "test", DishType dishType = DishType.Pepperoni, double price = 1, string? orderId = null)
+        => new(id, name, dishType, price, orderId ?? Guid.NewGuid().ToString());
+
+    private Dish? GetDishFromDatabaseById(string id) => AndDietCokeDbContext.Dishes.FirstOrDefault(x => x.Id == id);
+
+    private static void AssertElement(Dish? actual, DishDataModel expected)
+    {
+        Assert.That(actual, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(actual.Id, Is.EqualTo(expected.Id));
+            Assert.That(actual.Name, Is.EqualTo(expected.Name));
+            Assert.That(actual.DishType, Is.EqualTo(expected.DishType));
+            Assert.That(actual.Price, Is.EqualTo(expected.Price));
+        });
+    }
+}

AndDietCokeProject/AndDietCokeTests/StorageContractTests/EmployeeStorageContractTests.cs

@@ -0,0 +1,226 @@
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Enums;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeDatabase.Implementations;
+using AndDietCokeDatabase.Models;
+using Microsoft.EntityFrameworkCore;
+
+namespace AndDietCokeTests.StorageContractTests;
+
+[TestFixture]
+internal class EmployeeStorageContractTests : BaseStorageContractTest
+{
+    private EmployeeStorageContract _workerStorageContract;
+
+    [SetUp]
+    public void SetUp()
+    {
+        _workerStorageContract = new EmployeeStorageContract(AndDietCokeDbContext);
+    }
+
+    [TearDown]
+    public void TearDown()
+    {
+        AndDietCokeDbContext.Database.ExecuteSqlRaw("TRUNCATE \"Employees\" CASCADE;");
+    }
+
+    [Test]
+    public void Try_GetList_WhenHaveRecords_Test()
+    {
+        var worker = InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 1");
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 2");
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 3");
+        var list = _workerStorageContract.GetList();
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(3));
+        AssertElement(list.First(), worker);
+    }
+
+    [Test]
+    public void Try_GetList_WhenNoRecords_Test()
+    {
+        var list = _workerStorageContract.GetList();
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Is.Empty);
+    }
+
+    [Test]
+    public void Try_GetList_ByPostId_Test()
+    {
+        var postId = Guid.NewGuid().ToString();
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 1", postId);
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 2", postId);
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 3");
+        var list = _workerStorageContract.GetList(postId: postId);
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(2));
+        Assert.That(list.All(x => x.PositionId == postId));
+    }
+
+    [Test]
+    public void Try_GetList_ByBirthDate_Test()
+    {
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 1", birthDate: DateTime.UtcNow.AddYears(-25));
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 2", birthDate: DateTime.UtcNow.AddYears(-21));
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 3", birthDate: DateTime.UtcNow.AddYears(-20));
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 4", birthDate: DateTime.UtcNow.AddYears(-19));
+        var list = _workerStorageContract.GetList(fromBirthDate: DateTime.UtcNow.AddYears(-21).AddMinutes(-1), toBirthDate: DateTime.UtcNow.AddYears(-20).AddMinutes(1));
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(2));
+    }
+
+    [Test]
+    public void Try_GetList_ByEmploymentDate_Test()
+    {
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 1", employmentDate: DateTime.UtcNow.AddDays(-2));
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 2", employmentDate: DateTime.UtcNow.AddDays(-1));
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 3", employmentDate: DateTime.UtcNow.AddDays(1));
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 4", employmentDate: DateTime.UtcNow.AddDays(2));
+        var list = _workerStorageContract.GetList(fromEmploymentDate: DateTime.UtcNow.AddDays(-1).AddMinutes(-1), toEmploymentDate: DateTime.UtcNow.AddDays(1).AddMinutes(1));
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(2));
+    }
+
+    [Test]
+    public void Try_GetList_ByAllParameters_Test()
+    {
+        var postId = Guid.NewGuid().ToString();
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 1", postId, birthDate: DateTime.UtcNow.AddYears(-25), employmentDate: DateTime.UtcNow.AddDays(-2));
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 2", postId, birthDate: DateTime.UtcNow.AddYears(-22), employmentDate: DateTime.UtcNow.AddDays(-1));
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 3", postId, birthDate: DateTime.UtcNow.AddYears(-21), employmentDate: DateTime.UtcNow.AddDays(-1));
+        InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString(), "fio 4", birthDate: DateTime.UtcNow.AddYears(-20), employmentDate: DateTime.UtcNow.AddDays(1));
+        var list = _workerStorageContract.GetList(postId: postId, fromBirthDate: DateTime.UtcNow.AddYears(-21).AddMinutes(-1), toBirthDate: DateTime.UtcNow.AddYears(-20).AddMinutes(1), fromEmploymentDate: DateTime.UtcNow.AddDays(-1).AddMinutes(-1), toEmploymentDate: DateTime.UtcNow.AddDays(1).AddMinutes(1));
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(1));
+    }
+
+    [Test]
+    public void Try_GetElementById_WhenHaveRecord_Test()
+    {
+        var worker = InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString());
+        AssertElement(_workerStorageContract.GetElementById(worker.Id), worker);
+    }
+
+    [Test]
+    public void Try_GetElementById_WhenNoRecord_Test()
+    {
+        Assert.That(() => _workerStorageContract.GetElementById(Guid.NewGuid().ToString()), Is.Null);
+    }
+
+    [Test]
+    public void Try_GetElementByFIO_WhenHaveRecord_Test()
+    {
+        var worker = InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString());
+        AssertElement(_workerStorageContract.GetElementByFIO(worker.FIO), worker);
+    }
+
+    [Test]
+    public void Try_GetElementByFIO_WhenNoRecord_Test()
+    {
+        Assert.That(() => _workerStorageContract.GetElementByFIO("New Fio"), Is.Null);
+    }
+
+    [Test]
+    public void Try_AddElement_Test()
+    {
+        var worker = CreateModel(Guid.NewGuid().ToString());
+        _workerStorageContract.AddElement(worker);
+        AssertElement(GetEmployeeFromDatabase(worker.Id), worker);
+    }
+
+    [Test]
+    public void Try_AddElement_WhenHaveRecordWithSameId_Test()
+    {
+        var worker = CreateModel(Guid.NewGuid().ToString());
+        InsertEmployeeToDatabaseAndReturn(worker.Id);
+        Assert.That(() => _workerStorageContract.AddElement(worker), Throws.TypeOf<ElementExistsException>());
+    }
+
+    [Test]
+    public void Try_UpdElement_Test()
+    {
+        var worker = CreateModel(Guid.NewGuid().ToString(), "New Fio");
+        InsertEmployeeToDatabaseAndReturn(worker.Id);
+        _workerStorageContract.UpdElement(worker);
+        AssertElement(GetEmployeeFromDatabase(worker.Id), worker);
+    }
+
+    [Test]
+    public void Try_UpdElement_WhenNoRecordWithThisId_Test()
+    {
+        Assert.That(() => _workerStorageContract.UpdElement(CreateModel(Guid.NewGuid().ToString())), Throws.TypeOf<ElementNotFoundException>());
+    }
+
+    [Test]
+    public void Try_UpdElement_WhenNoRecordWasDeleted_Test()
+    {
+        var worker = CreateModel(Guid.NewGuid().ToString());
+        InsertEmployeeToDatabaseAndReturn(worker.Id, isDeleted: true);
+        Assert.That(() => _workerStorageContract.UpdElement(worker), Throws.TypeOf<ElementNotFoundException>());
+    }
+
+    [Test]
+    public void Try_DelElement_Test()
+    {
+        var worker = InsertEmployeeToDatabaseAndReturn(Guid.NewGuid().ToString());
+        _workerStorageContract.DelElement(worker.Id);
+        var element = GetEmployeeFromDatabase(worker.Id);
+        Assert.That(element, Is.Not.Null);
+        Assert.That(element.IsDeleted);
+    }
+
+    [Test]
+    public void Try_DelElement_WhenNoRecordWithThisId_Test()
+    {
+        Assert.That(() => _workerStorageContract.DelElement(Guid.NewGuid().ToString()), Throws.TypeOf<ElementNotFoundException>());
+    }
+
+    [Test]
+    public void Try_DelElement_WhenNoRecordWasDeleted_Test()
+    {
+        var worker = CreateModel(Guid.NewGuid().ToString());
+        InsertEmployeeToDatabaseAndReturn(worker.Id, isDeleted: true);
+        Assert.That(() => _workerStorageContract.DelElement(worker.Id), Throws.TypeOf<ElementNotFoundException>());
+    }
+
+    private Employee InsertEmployeeToDatabaseAndReturn(string id, string fio = "test", string? postId = null, PositionType positionType = PositionType.Assistant, DateTime? birthDate = null, DateTime? employmentDate = null, bool isDeleted = false)
+    {
+        var worker = new Employee() { Id = id, FIO = fio, PositionId = postId ?? Guid.NewGuid().ToString(), PositionType = positionType, BirthDate = birthDate ?? DateTime.UtcNow.AddYears(-20), EmploymentDate = employmentDate ?? DateTime.UtcNow, IsDeleted = isDeleted };
+        AndDietCokeDbContext.Employees.Add(worker);
+        AndDietCokeDbContext.SaveChanges();
+        return worker;
+    }
+
+    private static void AssertElement(EmployeeDataModel? actual, Employee expected)
+    {
+        Assert.That(actual, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(actual.Id, Is.EqualTo(expected.Id));
+            Assert.That(actual.PositionId, Is.EqualTo(expected.PositionId));
+            Assert.That(actual.FIO, Is.EqualTo(expected.FIO));
+            Assert.That(actual.BirthDate, Is.EqualTo(expected.BirthDate));
+            Assert.That(actual.EmploymentDate, Is.EqualTo(expected.EmploymentDate));
+            Assert.That(actual.IsDeleted, Is.EqualTo(expected.IsDeleted));
+        });
+    }
+
+    private static EmployeeDataModel CreateModel(string id, string fio = "fio", string? positionId = null, PositionType positionType = PositionType.Assistant, DateTime? birthDate = null, DateTime? employmentDate = null, bool isDeleted = false) =>
+        new(id, fio, positionId ?? Guid.NewGuid().ToString(), positionType, birthDate ?? DateTime.UtcNow.AddYears(-20), employmentDate ?? DateTime.UtcNow, isDeleted);
+
+    private Employee? GetEmployeeFromDatabase(string id) => AndDietCokeDbContext.Employees.FirstOrDefault(x => x.Id == id);
+
+    private static void AssertElement(Employee? actual, EmployeeDataModel expected)
+    {
+        Assert.That(actual, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(actual.Id, Is.EqualTo(expected.Id));
+            Assert.That(actual.PositionId, Is.EqualTo(expected.PositionId));
+            Assert.That(actual.FIO, Is.EqualTo(expected.FIO));
+            Assert.That(actual.BirthDate, Is.EqualTo(expected.BirthDate));
+            Assert.That(actual.EmploymentDate, Is.EqualTo(expected.EmploymentDate));
+            Assert.That(actual.IsDeleted, Is.EqualTo(expected.IsDeleted));
+        });
+    }
+}

AndDietCokeProject/AndDietCokeTests/StorageContractTests/OrderStorageContractTests.cs

@@ -0,0 +1,271 @@
+using AndDietCokeContracts.Enums;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeDatabase.Models;
+using AndDietCokeDatabase.Implementations;
+using Microsoft.EntityFrameworkCore;
+using AndDietCokeContracts.DataModels;
+
+namespace AndDietCokeTests.StorageContractTests;
+
+[TestFixture]
+internal class OrderStorageContractTests : BaseStorageContractTest
+{
+    private OrderStorageContract _ordertStorageContract;
+    private Client _client;
+    private Employee _employee;
+    private Dish _dish;
+
+    [SetUp]
+    public void SetUp()
+    {
+        _ordertStorageContract = new OrderStorageContract(AndDietCokeDbContext);
+        _client = InsertClientToDatabaseAndReturn();
+        _employee = InsertEmployeeToDatabaseAndReturn();
+        _dish = InsertDishToDatabaseAndReturn();
+    }
+
+    [TearDown]
+    public void TearDown()
+    {
+        AndDietCokeDbContext.Database.ExecuteSqlRaw("TRUNCATE \"Orders\" CASCADE;");
+        AndDietCokeDbContext.Database.ExecuteSqlRaw("TRUNCATE \"Clients\" CASCADE;");
+        AndDietCokeDbContext.Database.ExecuteSqlRaw("TRUNCATE \"Employees\" CASCADE;");
+        AndDietCokeDbContext.Database.ExecuteSqlRaw("TRUNCATE \"Dishes\" CASCADE;");
+    }
+
+    [Test]
+    public void Try_GetList_WhenHaveRecords_Test()
+    {
+        var order = InsertOrderToDatabaseAndReturn(_employee.Id, _client.Id, products: [(_dish.Id, 1)]);
+        InsertOrderToDatabaseAndReturn(_employee.Id, _client.Id, products: [(_dish.Id, 5)]);
+        InsertOrderToDatabaseAndReturn(_employee.Id, null, products: [(_dish.Id, 10)]);
+        var list = _ordertStorageContract.GetList();
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(3));
+        AssertElement(list.First(x => x.Id == order.Id), order);
+    }
+
+    [Test]
+    public void Try_GetList_WhenNoRecords_Test()
+    {
+        var list = _ordertStorageContract.GetList();
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Is.Empty);
+    }
+
+    [Test]
+    public void Try_GetList_ByWorkerId_Test()
+    {
+        var worker = InsertEmployeeToDatabaseAndReturn("Other worker");
+        InsertOrderToDatabaseAndReturn(_employee.Id, _client.Id, products: [(_dish.Id, 1)]);
+        InsertOrderToDatabaseAndReturn(_employee.Id, _client.Id, products: [(_dish.Id, 1)]);
+        InsertOrderToDatabaseAndReturn(worker.Id, null, products: [(_dish.Id, 1)]);
+        var list = _ordertStorageContract.GetList(employeedId: _employee.Id);
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(2));
+        Assert.That(list.All(x => x.EmloyeedId == _employee.Id));
+    }
+
+    [Test]
+    public void Try_GetList_ByBuyerId_Test()
+    {
+        var buyer = InsertClientToDatabaseAndReturn("Other fio", "+8-888-888-88-88");
+        InsertOrderToDatabaseAndReturn(_employee.Id, _client.Id, products: [(_dish.Id, 1)]);
+        InsertOrderToDatabaseAndReturn(_employee.Id, _client.Id, products: [(_dish.Id, 1)]);
+        InsertOrderToDatabaseAndReturn(_employee.Id, buyer.Id, products: [(_dish.Id, 1)]);
+        InsertOrderToDatabaseAndReturn(_employee.Id, null, products: [(_dish.Id, 1)]);
+        var list = _ordertStorageContract.GetList(clientId: _client.Id);
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(2));
+        Assert.That(list.All(x => x.ClientId == _client.Id));
+    }
+
+    [Test]
+    public void Try_GetList_ByProductId_Test()
+    {
+        var product = InsertDishToDatabaseAndReturn("Other name");
+        InsertOrderToDatabaseAndReturn(_employee.Id, _client.Id, products: [(_dish.Id, 5)]);
+        InsertOrderToDatabaseAndReturn(_employee.Id, _client.Id, products: [(_dish.Id, 1), (product.Id, 4)]);
+        InsertOrderToDatabaseAndReturn(_employee.Id, null, products: [(product.Id, 1)]);
+        InsertOrderToDatabaseAndReturn(_employee.Id, null, products: [(product.Id, 1), (_dish.Id, 1)]);
+        var list = _ordertStorageContract.GetList(dishId: _dish.Id);
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(3));
+        Assert.That(list.All(x => x.Dishes.Any(y => y.DishId == _dish.Id)));
+    }
+
+    [Test]
+    public void Try_GetList_ByAllParameters_Test()
+    {
+        var worker = InsertEmployeeToDatabaseAndReturn("Other worker");
+        var buyer = InsertClientToDatabaseAndReturn("Other fio", "+8-888-888-88-88");
+        var product = InsertDishToDatabaseAndReturn("Other name");
+        InsertOrderToDatabaseAndReturn(_employee.Id, _client.Id, products: [(_dish.Id, 1)]);
+        InsertOrderToDatabaseAndReturn(worker.Id, null, products: [(_dish.Id, 1)]);
+        InsertOrderToDatabaseAndReturn(worker.Id, _client.Id, products: [(_dish.Id, 1)]);
+        InsertOrderToDatabaseAndReturn(worker.Id, _client.Id, products: [(product.Id, 1)]);
+        InsertOrderToDatabaseAndReturn(_employee.Id, buyer.Id, products: [(_dish.Id, 1)]);
+        InsertOrderToDatabaseAndReturn(_employee.Id, _client.Id, products: [(product.Id, 1)]);
+        InsertOrderToDatabaseAndReturn(worker.Id, null, products: [(_dish.Id, 1)]);
+        var list = _ordertStorageContract.GetList(employeedId: _employee.Id, clientId: _client.Id, dishId: product.Id);
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(1));
+    }
+
+    [Test]
+    public void Try_GetElementById_WhenHaveRecord_Test()
+    {
+        var order = InsertOrderToDatabaseAndReturn(_employee.Id, _client.Id, products: [(_dish.Id, 1)]);
+        AssertElement(_ordertStorageContract.GetElementById(order.Id), order);
+    }
+
+    [Test]
+    public void Try_GetElementById_WhenNoRecord_Test()
+    {
+        InsertOrderToDatabaseAndReturn(_employee.Id, _client.Id, products: [(_dish.Id, 1)]);
+        Assert.That(() => _ordertStorageContract.GetElementById(Guid.NewGuid().ToString()), Is.Null);
+    }
+
+    [Test]
+    public void Try_GetElementById_WhenRecordHasCanceled_Test()
+    {
+        var order = InsertOrderToDatabaseAndReturn(_employee.Id, _client.Id, products: [(_dish.Id, 1)]);
+        AssertElement(_ordertStorageContract.GetElementById(order.Id), order);
+    }
+
+    [Test]
+    public void Try_AddElement_Test()
+    {
+        var order = CreateModel(Guid.NewGuid().ToString(), _employee.Id, _client.Id, [_dish.Id]);
+        _ordertStorageContract.AddElement(order);
+        AssertElement(GetOrderFromDatabaseById(order.Id), order);
+    }
+
+    [Test]
+    public void Try_AddElement_WhenIsDeletedIsTrue_Test()
+    {
+        var order = CreateModel(Guid.NewGuid().ToString(), _employee.Id, _client.Id,[_dish.Id]);
+        Assert.That(() => _ordertStorageContract.AddElement(order), Throws.Nothing);
+        AssertElement(GetOrderFromDatabaseById(order.Id), CreateModel(order.Id, _employee.Id, _client.Id, [_dish.Id]));
+    }
+
+    [Test]
+    public void Try_DelElement_Test()
+    {
+        var order = InsertOrderToDatabaseAndReturn(_employee.Id, _client.Id, products: [(_dish.Id, 1)]);
+        _ordertStorageContract.DelElement(order.Id);
+        var element = GetOrderFromDatabaseById(order.Id);
+        Assert.That(element, Is.Null);
+    }
+
+    [Test]
+    public void Try_DelElement_WhenNoRecordWithThisId_Test()
+    {
+        Assert.That(() => _ordertStorageContract.DelElement(Guid.NewGuid().ToString()), Throws.TypeOf<ElementNotFoundException>());
+    }
+
+    private Client InsertClientToDatabaseAndReturn(string fio = "test", string phoneNumber = "+7-777-777-77-77")
+    {
+        var buyer = new Client() { Id = Guid.NewGuid().ToString(), FIO = fio, Contact = phoneNumber, DiscountSize = 10 };
+        AndDietCokeDbContext.Clients.Add(buyer);
+        AndDietCokeDbContext.SaveChanges();
+        return buyer;
+    }
+
+    private Employee InsertEmployeeToDatabaseAndReturn(string fio = "test")
+    {
+        var worker = new Employee() { Id = Guid.NewGuid().ToString(), FIO = fio, PositionId = Guid.NewGuid().ToString() };
+        AndDietCokeDbContext.Employees.Add(worker);
+        AndDietCokeDbContext.SaveChanges();
+        return worker;
+    }
+
+    private Dish InsertDishToDatabaseAndReturn(string name = "test", DishType dishType = DishType.Pepperoni, double price = 1, string? orderId = null)
+    {
+        var product = new Dish() { Id = Guid.NewGuid().ToString(), Name = name, DishType = dishType, Price = price, OrderId = orderId ?? Guid.NewGuid().ToString() };
+        AndDietCokeDbContext.Dishes.Add(product);
+        AndDietCokeDbContext.SaveChanges();
+        return product;
+    }
+
+    private Order InsertOrderToDatabaseAndReturn(string employeeId, string? clientId, List<(string, int)>? products = null)
+    {
+        var order = new Order() { EmloyeedId = employeeId, ClientId = clientId, OrderDishes = [] };
+        if (products is not null)
+        {
+            foreach (var elem in products)
+            {
+                order.OrderDishes.Add(new Dish_Order { DishId = elem.Item1, OrderId = order.Id, Count = elem.Item2 });
+            }
+        }
+        AndDietCokeDbContext.Orders.Add(order);
+        AndDietCokeDbContext.SaveChanges();
+        return order;
+    }
+
+    private static void AssertElement(OrderDataModels? actual, Order expected)
+    {
+        Assert.That(actual, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(actual.Id, Is.EqualTo(expected.Id));
+            Assert.That(actual.EmloyeedId, Is.EqualTo(expected.EmloyeedId));
+            Assert.That(actual.ClientId, Is.EqualTo(expected.ClientId)); ;
+        });
+
+        if (expected.OrderDishes is not null)
+        {
+            Assert.That(actual.Dishes, Is.Not.Null);
+            Assert.That(actual.Dishes, Has.Count.EqualTo(expected.OrderDishes.Count));
+            for (int i = 0; i < actual.Dishes.Count; ++i)
+            {
+                Assert.Multiple(() =>
+                {
+                    Assert.That(actual.Dishes[i].DishId, Is.EqualTo(expected.OrderDishes[i].DishId));
+                    Assert.That(actual.Dishes[i].Count, Is.EqualTo(expected.OrderDishes[i].Count));
+                });
+            }
+        }
+        else
+        {
+            Assert.That(actual.Dishes, Is.Null);
+        }
+    }
+
+    private static OrderDataModels CreateModel(string id, string employeeId, string clientId, List<string> productIds)
+    {
+        var products = productIds.Select(x => new Dish_OrderDataModel(id, x, 1)).ToList();
+        return new(id, clientId, employeeId, products);
+    }
+
+    private Order? GetOrderFromDatabaseById(string id) => AndDietCokeDbContext.Orders.Include(x => x.OrderDishes).FirstOrDefault(x => x.Id == id);
+
+    private static void AssertElement(Order? actual, OrderDataModels expected)
+    {
+        Assert.That(actual, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(actual.Id, Is.EqualTo(expected.Id));
+            Assert.That(actual.EmloyeedId, Is.EqualTo(expected.EmloyeedId));
+            Assert.That(actual.ClientId, Is.EqualTo(expected.ClientId));;
+        });
+
+        if (expected.Dishes is not null)
+        {
+            Assert.That(actual.OrderDishes, Is.Not.Null);
+            Assert.That(actual.OrderDishes, Has.Count.EqualTo(expected.Dishes.Count));
+            for (int i = 0; i < actual.OrderDishes.Count; ++i)
+            {
+                Assert.Multiple(() =>
+                {
+                    Assert.That(actual.OrderDishes[i].DishId, Is.EqualTo(expected.Dishes[i].DishId));
+                    Assert.That(actual.OrderDishes[i].Count, Is.EqualTo(expected.Dishes[i].Count));
+                });
+            }
+        }
+        else
+        {
+            Assert.That(actual.OrderDishes, Is.Null);
+        }
+    }
+}

AndDietCokeProject/AndDietCokeTests/StorageContractTests/PositionStorageContractTests.cs

@@ -0,0 +1,317 @@
+using AndDietCokeContracts.DataModels;
+using AndDietCokeContracts.Enums;
+using AndDietCokeContracts.Exceptions;
+using AndDietCokeDatabase.Implementations;
+using AndDietCokeDatabase.Models;
+using Microsoft.EntityFrameworkCore;
+
+namespace AndDietCokeTests.StorageContractTests;
+
+[TestFixture]
+internal class PositionStorageContractTests : BaseStorageContractTest
+{
+    private PositionStorageContract _postStorageContract;
+
+    [SetUp]
+    public void SetUp()
+    {
+        _postStorageContract = new PositionStorageContract(AndDietCokeDbContext);
+    }
+
+    [TearDown]
+    public void TearDown()
+    {
+        AndDietCokeDbContext.Database.ExecuteSqlRaw("TRUNCATE \"Posts\" CASCADE;");
+    }
+
+    [Test]
+    public void Try_GetList_WhenHaveRecords_Test()
+    {
+        var post = InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 1");
+        InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 2");
+        InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 3");
+        var list = _postStorageContract.GetList();
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(3));
+        AssertElement(list.First(x => x.Id == post.PositionId), post);
+    }
+
+    [Test]
+    public void Try_GetList_WhenNoRecords_Test()
+    {
+        var list = _postStorageContract.GetList();
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Is.Empty);
+    }
+
+    [Test]
+    public void Try_GetList_OnlyActual_Test()
+    {
+        InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 1", isActual: true);
+        InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 2", isActual: true);
+        InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 3", isActual: false);
+        var list = _postStorageContract.GetList(onlyActual: true);
+        Assert.That(list, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(list, Has.Count.EqualTo(2));
+            Assert.That(!list.Any(x => !x.IsActual));
+        });
+    }
+
+    [Test]
+    public void Try_GetList_IncludeNoActual_Test()
+    {
+        InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 1", isActual: true);
+        InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 2", isActual: true);
+        InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 3", isActual: false);
+        var list = _postStorageContract.GetList(onlyActual: false);
+        Assert.That(list, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(list, Has.Count.EqualTo(3));
+            Assert.That(list.Count(x => x.IsActual), Is.EqualTo(2));
+            Assert.That(list.Count(x => !x.IsActual), Is.EqualTo(1));
+        });
+    }
+
+    [Test]
+    public void Try_GetPostWithHistory_WhenHaveRecords_Test()
+    {
+        var PositionId = Guid.NewGuid().ToString();
+        InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 1", isActual: true);
+        InsertPostToDatabaseAndReturn(PositionId, "name 2", isActual: true);
+        InsertPostToDatabaseAndReturn(PositionId, "name 2", isActual: false);
+        var list = _postStorageContract.GetPostWithHistory(PositionId);
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(2));
+    }
+
+    [Test]
+    public void Try_GetPostWithHistory_WhenNoRecords_Test()
+    {
+        var PositionId = Guid.NewGuid().ToString();
+        InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), "name 1", isActual: true);
+        InsertPostToDatabaseAndReturn(PositionId, "name 2", isActual: true);
+        InsertPostToDatabaseAndReturn(PositionId, "name 2", isActual: false);
+        var list = _postStorageContract.GetPostWithHistory(Guid.NewGuid().ToString());
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(0));
+    }
+
+    [Test]
+    public void Try_GetElementById_WhenHaveRecord_Test()
+    {
+        var post = InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString());
+        AssertElement(_postStorageContract.GetElementById(post.PositionId), post);
+    }
+
+    [Test]
+    public void Try_GetElementById_WhenNoRecord_Test()
+    {
+        InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString());
+        Assert.That(() => _postStorageContract.GetElementById(Guid.NewGuid().ToString()), Is.Null);
+    }
+
+    [Test]
+    public void Try_GetElementById_WhenRecordHasDeleted_Test()
+    {
+        var post = InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), isActual: false);
+        Assert.That(() => _postStorageContract.GetElementById(post.PositionId), Is.Null);
+    }
+
+    [Test]
+    public void Try_GetElementById_WhenTrySearchById_Test()
+    {
+        var post = InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString());
+        Assert.That(() => _postStorageContract.GetElementById(post.Id), Is.Null);
+    }
+
+    [Test]
+    public void Try_GetElementByName_WhenHaveRecord_Test()
+    {
+        var post = InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString());
+        AssertElement(_postStorageContract.GetElementByName(post.PositionName), post);
+    }
+
+    [Test]
+    public void Try_GetElementByName_WhenNoRecord_Test()
+    {
+        InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString());
+        Assert.That(() => _postStorageContract.GetElementByName("name"), Is.Null);
+    }
+
+    [Test]
+    public void Try_GetElementByName_WhenRecordHasDeleted_Test()
+    {
+        var post = InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), isActual: false);
+        Assert.That(() => _postStorageContract.GetElementById(post.PositionName), Is.Null);
+    }
+
+    [Test]
+    public void Try_AddElement_Test()
+    {
+        var post = CreateModel(Guid.NewGuid().ToString(), isActual: true);
+        _postStorageContract.AddElement(post);
+        AssertElement(GetPostFromDatabaseByPositionId(post.Id), post);
+    }
+
+    [Test]
+    public void Try_AddElement_WhenActualIsFalse_Test()
+    {
+        var post = CreateModel(Guid.NewGuid().ToString(), isActual: false);
+        Assert.That(() => _postStorageContract.AddElement(post), Throws.Nothing);
+        AssertElement(GetPostFromDatabaseByPositionId(post.Id), CreateModel(post.Id, isActual: true));
+    }
+
+    [Test]
+    public void Try_AddElement_WhenHaveRecordWithSameName_Test()
+    {
+        var post = CreateModel(Guid.NewGuid().ToString(), "name unique", isActual: true);
+        InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), postName: post.PositionName, isActual: true);
+        Assert.That(() => _postStorageContract.AddElement(post), Throws.TypeOf<ElementExistsException>());
+    }
+
+    [Test]
+    public void Try_AddElement_WhenHaveRecordWithSamePositionIdAndActualIsTrue_Test()
+    {
+        var post = CreateModel(Guid.NewGuid().ToString(), isActual: true);
+        InsertPostToDatabaseAndReturn(post.Id, isActual: true);
+        Assert.That(() => _postStorageContract.AddElement(post), Throws.TypeOf<ElementExistsException>());
+    }
+
+    [Test]
+    public void Try_UpdElement_Test()
+    {
+        var post = CreateModel(Guid.NewGuid().ToString());
+        InsertPostToDatabaseAndReturn(post.Id, isActual: true);
+        _postStorageContract.UpdElement(post);
+        var posts = AndDietCokeDbContext.Posts.Where(x => x.PositionId == post.Id).OrderByDescending(x => x.ChangeDate);
+        Assert.That(posts.Count(), Is.EqualTo(2));
+        AssertElement(posts.First(), CreateModel(post.Id, isActual: true));
+        AssertElement(posts.Last(), CreateModel(post.Id, isActual: false));
+    }
+
+    [Test]
+    public void Try_UpdElement_WhenActualIsFalse_Test()
+    {
+        var post = CreateModel(Guid.NewGuid().ToString(), isActual: false);
+        InsertPostToDatabaseAndReturn(post.Id, isActual: true);
+        _postStorageContract.UpdElement(post);
+        AssertElement(GetPostFromDatabaseByPositionId(post.Id), CreateModel(post.Id, isActual: true));
+    }
+
+    [Test]
+    public void Try_UpdElement_WhenNoRecordWithThisId_Test()
+    {
+        Assert.That(() => _postStorageContract.UpdElement(CreateModel(Guid.NewGuid().ToString())), Throws.TypeOf<ElementNotFoundException>());
+    }
+
+    [Test]
+    public void Try_UpdElement_WhenHaveRecordWithSameName_Test()
+    {
+        var post = CreateModel(Guid.NewGuid().ToString(), "New Name");
+        InsertPostToDatabaseAndReturn(post.Id, postName: "name");
+        InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), postName: post.PositionName);
+        Assert.That(() => _postStorageContract.UpdElement(post), Throws.TypeOf<ElementExistsException>());
+    }
+
+    [Test]
+    public void Try_UpdElement_WhenRecordWasDeleted_Test()
+    {
+        var post = CreateModel(Guid.NewGuid().ToString());
+        InsertPostToDatabaseAndReturn(post.Id, isActual: false);
+        Assert.That(() => _postStorageContract.UpdElement(post), Throws.TypeOf<ElementDeletedException>());
+    }
+
+    [Test]
+    public void Try_DelElement_Test()
+    {
+        var post = InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), isActual: true);
+        _postStorageContract.DelElement(post.PositionId);
+        var element = GetPostFromDatabaseByPositionId(post.PositionId);
+        Assert.Multiple(() =>
+        {
+            Assert.That(element, Is.Not.Null);
+            Assert.That(!element!.IsActual);
+        });
+    }
+
+    [Test]
+    public void Try_DelElement_WhenNoRecordWithThisId_Test()
+    {
+        Assert.That(() => _postStorageContract.DelElement(Guid.NewGuid().ToString()), Throws.TypeOf<ElementNotFoundException>());
+    }
+
+    [Test]
+    public void Try_DelElement_WhenRecordWasDeleted_Test()
+    {
+        var post = InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), isActual: false);
+        Assert.That(() => _postStorageContract.DelElement(post.PositionId), Throws.TypeOf<ElementDeletedException>());
+    }
+
+    [Test]
+    public void Try_ResElement_Test()
+    {
+        var post = InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), isActual: false);
+        _postStorageContract.ResElement(post.PositionId);
+        var element = GetPostFromDatabaseByPositionId(post.PositionId);
+        Assert.Multiple(() =>
+        {
+            Assert.That(element, Is.Not.Null);
+            Assert.That(element!.IsActual);
+        });
+    }
+
+    [Test]
+    public void Try_ResElement_WhenNoRecordWithThisId_Test()
+    {
+        Assert.That(() => _postStorageContract.ResElement(Guid.NewGuid().ToString()), Throws.TypeOf<ElementNotFoundException>());
+    }
+
+    [Test]
+    public void Try_ResElement_WhenRecordNotWasDeleted_Test()
+    {
+        var post = InsertPostToDatabaseAndReturn(Guid.NewGuid().ToString(), isActual: true);
+        Assert.That(() => _postStorageContract.ResElement(post.PositionId), Throws.Nothing);
+    }
+
+    private Position InsertPostToDatabaseAndReturn(string id, string postName = "test", PositionType postType = PositionType.Assistant, double salary = 10, bool isActual = true, DateTime? changeDate = null)
+    {
+        var post = new Position() { Id = Guid.NewGuid().ToString(), PositionId = id, PositionName = postName, PositionType = postType, Salary = salary, IsActual = isActual, ChangeDate = changeDate ?? DateTime.UtcNow };
+        AndDietCokeDbContext.Posts.Add(post);
+        AndDietCokeDbContext.SaveChanges();
+        return post;
+    }
+
+    private static void AssertElement(PositionDataModel? actual, Position expected)
+    {
+        Assert.That(actual, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(actual.Id, Is.EqualTo(expected.PositionId));
+            Assert.That(actual.PositionName, Is.EqualTo(expected.PositionName));
+            Assert.That(actual.PositionType, Is.EqualTo(expected.PositionType));
+            Assert.That(actual.Salary, Is.EqualTo(expected.Salary));
+            Assert.That(actual.IsActual, Is.EqualTo(expected.IsActual));
+        });
+    }
+
+    private static PositionDataModel CreateModel(string PositionId, string postName = "test", PositionType postType = PositionType.Assistant, double salary = 10, bool isActual = false, DateTime? changeDate = null)
+        => new(PositionId, postName, postType, salary, isActual, changeDate ?? DateTime.UtcNow);
+
+    private Position? GetPostFromDatabaseByPositionId(string id) => AndDietCokeDbContext.Posts.Where(x => x.PositionId == id).OrderByDescending(x => x.ChangeDate).FirstOrDefault();
+
+    private static void AssertElement(Position? actual, PositionDataModel expected)
+    {
+        Assert.That(actual, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(actual.PositionId, Is.EqualTo(expected.Id));
+            Assert.That(actual.PositionName, Is.EqualTo(expected.PositionName));
+            Assert.That(actual.PositionType, Is.EqualTo(expected.PositionType));
+            Assert.That(actual.Salary, Is.EqualTo(expected.Salary));
+            Assert.That(actual.IsActual, Is.EqualTo(expected.IsActual));
+        });
+    }
+}

AndDietCokeProject/AndDietCokeTests/StorageContractTests/SalaryStorageContractTests.cs

@@ -0,0 +1,148 @@
+using AndDietCokeContracts.DataModels;
+using AndDietCokeDatabase.Implementations;
+using AndDietCokeDatabase.Models;
+using Microsoft.EntityFrameworkCore;
+
+namespace AndDietCokeTests.StorageContractTests;
+
+[TestFixture]
+internal class SalaryStorageContractTests : BaseStorageContractTest
+{
+    private SalaryStorageContract _salaryStorageContract;
+    private Employee _employee;
+
+    [SetUp]
+    public void SetUp()
+    {
+        _salaryStorageContract = new SalaryStorageContract(AndDietCokeDbContext);
+        _employee = InsertWorkerToDatabaseAndReturn();
+    }
+
+    [TearDown]
+    public void TearDown()
+    {
+        AndDietCokeDbContext.Database.ExecuteSqlRaw("TRUNCATE \"Salaries\" CASCADE;");
+        AndDietCokeDbContext.Database.ExecuteSqlRaw("TRUNCATE \"Employees\" CASCADE;");
+    }
+
+    [Test]
+    public void Try_GetList_WhenHaveRecords_Test()
+    {
+        var salary = InsertSalaryToDatabaseAndReturn(_employee.Id, workerSalary: 100);
+        InsertSalaryToDatabaseAndReturn(_employee.Id);
+        InsertSalaryToDatabaseAndReturn(_employee.Id);
+        var list = _salaryStorageContract.GetList(DateTime.UtcNow.AddDays(-10), DateTime.UtcNow.AddDays(10));
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Has.Count.EqualTo(3));
+        AssertElement(list.First(), salary);
+    }
+
+    [Test]
+    public void Try_GetList_WhenNoRecords_Test()
+    {
+        var list = _salaryStorageContract.GetList(DateTime.UtcNow.AddDays(-10), DateTime.UtcNow.AddDays(10));
+        Assert.That(list, Is.Not.Null);
+        Assert.That(list, Is.Empty);
+    }
+
+    [Test]
+    public void Try_GetList_OnlyInDatePeriod_Test()
+    {
+        InsertSalaryToDatabaseAndReturn(_employee.Id, salaryDate: DateTime.UtcNow.AddDays(-2));
+        InsertSalaryToDatabaseAndReturn(_employee.Id, salaryDate: DateTime.UtcNow.AddDays(-1).AddMinutes(-5));
+        InsertSalaryToDatabaseAndReturn(_employee.Id, salaryDate: DateTime.UtcNow.AddDays(-1).AddMinutes(5));
+        InsertSalaryToDatabaseAndReturn(_employee.Id, salaryDate: DateTime.UtcNow.AddDays(1).AddMinutes(-5));
+        InsertSalaryToDatabaseAndReturn(_employee.Id, salaryDate: DateTime.UtcNow.AddDays(1).AddMinutes(5));
+        InsertSalaryToDatabaseAndReturn(_employee.Id, salaryDate: DateTime.UtcNow.AddDays(-2));
+        var list = _salaryStorageContract.GetList(DateTime.UtcNow.AddDays(-1), DateTime.UtcNow.AddDays(1));
+        Assert.That(list, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(list, Has.Count.EqualTo(2));
+        });
+    }
+
+    [Test]
+    public void Try_GetList_ByWorker_Test()
+    {
+        var worker = InsertWorkerToDatabaseAndReturn("name 2");
+        InsertSalaryToDatabaseAndReturn(_employee.Id);
+        InsertSalaryToDatabaseAndReturn(_employee.Id);
+        InsertSalaryToDatabaseAndReturn(worker.Id);
+        var list = _salaryStorageContract.GetList(DateTime.UtcNow.AddDays(-1), DateTime.UtcNow.AddDays(1), _employee.Id);
+        Assert.That(list, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(list, Has.Count.EqualTo(2));
+            Assert.That(list.All(x => x.EmloyeedId == _employee.Id));
+        });
+    }
+
+    [Test]
+    public void Try_GetList_ByWorkerOnlyInDatePeriod_Test()
+    {
+        var worker = InsertWorkerToDatabaseAndReturn("name 2");
+        InsertSalaryToDatabaseAndReturn(_employee.Id, salaryDate: DateTime.UtcNow.AddDays(-2));
+        InsertSalaryToDatabaseAndReturn(_employee.Id, salaryDate: DateTime.UtcNow.AddDays(-1).AddMinutes(5));
+        InsertSalaryToDatabaseAndReturn(worker.Id, salaryDate: DateTime.UtcNow.AddDays(-1).AddMinutes(5));
+        InsertSalaryToDatabaseAndReturn(_employee.Id, salaryDate: DateTime.UtcNow.AddDays(1).AddMinutes(-5));
+        InsertSalaryToDatabaseAndReturn(worker.Id, salaryDate: DateTime.UtcNow.AddDays(1).AddMinutes(-5));
+        InsertSalaryToDatabaseAndReturn(_employee.Id, salaryDate: DateTime.UtcNow.AddDays(-2));
+        var list = _salaryStorageContract.GetList(DateTime.UtcNow.AddDays(-1), DateTime.UtcNow.AddDays(1), _employee.Id);
+        Assert.That(list, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(list, Has.Count.EqualTo(2));
+            Assert.That(list.All(x => x.EmloyeedId == _employee.Id));
+        });
+    }
+
+    [Test]
+    public void Try_AddElement_Test()
+    {
+        var salary = CreateModel(_employee.Id);
+        _salaryStorageContract.AddElement(salary);
+        AssertElement(GetSalaryFromDatabaseByWorkerId(_employee.Id), salary);
+    }
+
+    private Employee InsertWorkerToDatabaseAndReturn(string workerFIO = "fio")
+    {
+        var worker = new Employee() { Id = Guid.NewGuid().ToString(), PositionId = Guid.NewGuid().ToString(), FIO = workerFIO, IsDeleted = false };
+        AndDietCokeDbContext.Employees.Add(worker);
+        AndDietCokeDbContext.SaveChanges();
+        return worker;
+    }
+
+    private Salaries InsertSalaryToDatabaseAndReturn(string workerId, double workerSalary = 1, DateTime? salaryDate = null)
+    {
+        var salary = new Salaries() { EmloyeedId = workerId, Salary = workerSalary, SalaryDate = salaryDate ?? DateTime.UtcNow };
+        AndDietCokeDbContext.Salaries.Add(salary);
+        AndDietCokeDbContext.SaveChanges();
+        return salary;
+    }
+
+    private static void AssertElement(SalaryDataModel? actual, Salaries expected)
+    {
+        Assert.That(actual, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(actual.EmloyeedId, Is.EqualTo(expected.EmloyeedId));
+            Assert.That(actual.Salary, Is.EqualTo(expected.Salary));
+        });
+    }
+
+    private static SalaryDataModel CreateModel(string workerId, double workerSalary = 1, DateTime? salaryDate = null)
+        => new(workerId, salaryDate ?? DateTime.UtcNow, workerSalary, workerId);
+
+    private Salaries? GetSalaryFromDatabaseByWorkerId(string id) => AndDietCokeDbContext.Salaries.FirstOrDefault(x => x.EmloyeedId == id);
+
+    private static void AssertElement(Salaries? actual, SalaryDataModel expected)
+    {
+        Assert.That(actual, Is.Not.Null);
+        Assert.Multiple(() =>
+        {
+            Assert.That(actual.EmloyeedId, Is.EqualTo(expected.EmloyeedId));
+            Assert.That(actual.Salary, Is.EqualTo(expected.Salary));
+        });
+    }
+}