diff --git a/.gitignore b/.gitignore
index ca1c7a3..2578d88 100644
--- a/.gitignore
+++ b/.gitignore
@@ -397,4 +397,4 @@ FodyWeavers.xsd
 
 # JetBrains Rider
 *.sln.iml
-
+*/*.idea
\ No newline at end of file
diff --git a/SoftwareInstallationTests/DataModelsTests/ClientDataModelTests.cs b/SoftwareInstallationTests/DataModelsTests/ClientDataModelTests.cs
new file mode 100644
index 0000000..7cd2460
--- /dev/null
+++ b/SoftwareInstallationTests/DataModelsTests/ClientDataModelTests.cs
@@ -0,0 +1,83 @@
+using SoftwareInstallationContracts.DataModels;
+using SoftwareInstallationContracts.Exceptions;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace SoftwareInstallationTests.DataModelsTests;
+
+[TestFixture]
+internal class ClientDataModelTests
+{
+    private ClientDataModel client;
+
+    [Test]
+    public void IdIsNullOrEmptyTest()
+    {
+        client = CreateDataModel(null, "Fio Fio Fio", "+7-777-777-77-77");
+        Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
+        client = CreateDataModel(string.Empty, "Fio Fio Fio", "+7-777-777-77-77");
+        Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void IdIsNotGuidTest()
+    {
+        client = CreateDataModel("id", "Fio Fio Fio", "+7-777-777-77-77");
+        Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void FIOIsNullOrEmptyTest()
+    {
+        client = CreateDataModel(Guid.NewGuid().ToString(), null, "+7-777-777-77-77");
+        Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
+        client = CreateDataModel(Guid.NewGuid().ToString(), string.Empty, "+7-777-777-77-77");
+        Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void FIOIsIncorrectTest()
+    {
+        client = CreateDataModel(Guid.NewGuid().ToString(), "fio", "+7-777-777-77-77");
+        Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void PhoneNumberIsNullOrEmptyTest()
+    {
+        client = CreateDataModel(Guid.NewGuid().ToString(), "Fio Fio Fio", null);
+        Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
+        client = CreateDataModel(Guid.NewGuid().ToString(), "Fio Fio Fio", string.Empty);
+        Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void PhoneNumberIsIncorrectTest()
+    {
+        client = CreateDataModel(Guid.NewGuid().ToString(), "Fio Fio Fio", "777");
+        Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void AllFieldsIsCorrectTest()
+    {
+        string phoneNumber = "+7-777-777-77-77";
+        string fio = "Vasiliy Vasilievich Vasiliev";
+        string id = Guid.NewGuid().ToString();
+        client = CreateDataModel(id, fio, phoneNumber);
+        Assert.That(() => client.Validate(), Throws.Nothing);
+
+        Assert.Multiple(() => 
+        {
+            Assert.That(client.Id, Is.EqualTo(id));
+            Assert.That(client.FIO, Is.EqualTo(fio));
+            Assert.That(client.PhoneNumber, Is.EqualTo(phoneNumber));
+        });
+    }
+
+    private static ClientDataModel CreateDataModel(string? id, string? fio, string? phoneNumber) =>
+new(id, fio, phoneNumber);
+}
diff --git a/SoftwareInstallationTests/DataModelsTests/CompanyDataModelTests.cs b/SoftwareInstallationTests/DataModelsTests/CompanyDataModelTests.cs
new file mode 100644
index 0000000..b65cd25
--- /dev/null
+++ b/SoftwareInstallationTests/DataModelsTests/CompanyDataModelTests.cs
@@ -0,0 +1,62 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using SoftwareInstallationContracts.DataModels;
+using SoftwareInstallationContracts.Exceptions;
+
+namespace SoftwareInstallationTests.DataModelsTests;
+
+[TestFixture]
+internal class CompanyDataModelTests
+{
+    private CompanyDataModel company;
+
+    [Test]
+    public void IdIsNullEmptyTest()
+    {
+        company = CreateDataModel(null, "name");
+        Assert.That(() => company.Validate(), Throws.TypeOf<ValidationFieldException>());
+        company = CreateDataModel(string.Empty, "name");
+        Assert.That(() => company.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void IdIsNotGuidTest()
+    {
+        company = CreateDataModel("id", "name");
+        Assert.That(() => company.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void companyNameIsNullOrEmptyTest()
+    {
+        company = CreateDataModel(Guid.NewGuid().ToString(), null);
+        Assert.That(() => company.Validate(), Throws.TypeOf<ValidationFieldException>());
+        company = CreateDataModel(Guid.NewGuid().ToString(), string.Empty);
+        Assert.That(() => company.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void AllFieldsIsCorrectTest()
+    {
+        string companyId = Guid.NewGuid().ToString();
+        string companyName = "name";
+        string prevcompanyName = "prevcompanyName";
+        string prevPrevcompanyName = "prevPrevcompanyName";
+        company = CreateDataModel(companyId, companyName, prevcompanyName, prevPrevcompanyName);
+        Assert.That(() => company.Validate(), Throws.Nothing);
+        Assert.Multiple(() =>
+        {
+            Assert.That(company.Id, Is.EqualTo(companyId));
+            Assert.That(company.CompanyName, Is.EqualTo(companyName));
+            Assert.That(company.PrevCompanyName, Is.EqualTo(prevcompanyName));
+            Assert.That(company.PrevPrevCompanyName, Is.EqualTo(prevPrevcompanyName));
+        });
+    }
+
+    private static CompanyDataModel CreateDataModel(string? id, string? companyName, string? prevcompanyName = null, string? prevPrevcompanyName = null) =>
+        new(id, companyName, prevcompanyName, prevPrevcompanyName);
+}
diff --git a/SoftwareInstallationTests/DataModelsTests/InstallationDataModelTests.cs b/SoftwareInstallationTests/DataModelsTests/InstallationDataModelTests.cs
new file mode 100644
index 0000000..981e8b1
--- /dev/null
+++ b/SoftwareInstallationTests/DataModelsTests/InstallationDataModelTests.cs
@@ -0,0 +1,99 @@
+using SoftwareInstallationContracts.DataModels;
+using SoftwareInstallationContracts.Exceptions;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace SoftwareInstallationTests.DataModelsTests;
+
+[TestFixture]
+internal class InstallationDataModelTests
+{
+    private InstallationDataModel installation;
+
+    [Test]
+    public void IdIsNullOrEmptyTest()
+    {
+        installation = CreateDataModel(null, Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 10, false, CreateSubDataModel());
+        Assert.That(() => installation.Validate(), Throws.TypeOf<ValidationFieldException>());
+        installation = CreateDataModel(string.Empty, Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 10, false, CreateSubDataModel());
+        Assert.That(() => installation.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void IdIsNotGuidTest()
+    {
+        installation = CreateDataModel("id", Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 10, false, CreateSubDataModel());
+        Assert.That(() => installation.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+    [Test]
+    public void WorkerIdIsNullOrEmptyTest()
+    {
+        installation = CreateDataModel(Guid.NewGuid().ToString(), null, Guid.NewGuid().ToString(), 10, false, CreateSubDataModel());
+        Assert.That(() => installation.Validate(), Throws.TypeOf<ValidationFieldException>());
+        installation = CreateDataModel(Guid.NewGuid().ToString(), string.Empty, Guid.NewGuid().ToString(), 10, false, CreateSubDataModel());
+        Assert.That(() => installation.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void WorkerIdIsNotGuidTest()
+    {
+        installation = CreateDataModel(Guid.NewGuid().ToString(), "workerId", Guid.NewGuid().ToString(), 10, false, CreateSubDataModel());
+        Assert.That(() => installation.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void ClientIdIsNotGuidTest()
+    {
+        installation = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), "clientId", 10, false, CreateSubDataModel());
+        Assert.That(() => installation.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void SumIsLessOrZeroTest()
+    {
+        installation = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 0, false, CreateSubDataModel());
+        Assert.That(() => installation.Validate(), Throws.TypeOf<ValidationFieldException>());
+        installation = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), -10, false, CreateSubDataModel());
+        Assert.That(() => installation.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void SoftwaresIsNullOrEmptyTest()
+    {
+        installation = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 10, false, null);
+        Assert.That(() => installation.Validate(), Throws.TypeOf<ValidationFieldException>());
+        installation = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 10, false, []);
+        Assert.That(() => installation.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void AllFieldsIsCorrectTest()
+    {
+        string installationId = Guid.NewGuid().ToString();
+        string workerId = Guid.NewGuid().ToString();
+        string clientId = Guid.NewGuid().ToString();
+        double sum = 10;
+        bool isCancel = true;
+        List<InstallationSoftwareDataModel> softwares = CreateSubDataModel();
+        installation = CreateDataModel(installationId, workerId, clientId, sum, isCancel, softwares);
+        Assert.That(() => installation.Validate(), Throws.Nothing);
+        Assert.Multiple(() =>
+        {
+            Assert.That(installation.Id, Is.EqualTo(installationId));
+            Assert.That(installation.WorkerId, Is.EqualTo(workerId));
+            Assert.That(installation.ClientId, Is.EqualTo(clientId));
+            Assert.That(installation.Sum, Is.EqualTo(sum));
+            Assert.That(installation.IsCancel, Is.EqualTo(isCancel));
+            Assert.That(installation.Programs, Is.EquivalentTo(softwares));
+        });
+    }
+
+    private static InstallationDataModel CreateDataModel(string? id, string? workerId, string? clientId, double sum, bool isCancel, List<InstallationSoftwareDataModel>? softwares) =>
+        new(id, workerId, clientId, sum, isCancel, softwares);
+
+    private static List<InstallationSoftwareDataModel> CreateSubDataModel()
+        => [new(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 1)];
+}
diff --git a/SoftwareInstallationTests/DataModelsTests/InstallationSoftwareDataModelTests.cs b/SoftwareInstallationTests/DataModelsTests/InstallationSoftwareDataModelTests.cs
new file mode 100644
index 0000000..b81e079
--- /dev/null
+++ b/SoftwareInstallationTests/DataModelsTests/InstallationSoftwareDataModelTests.cs
@@ -0,0 +1,76 @@
+using SoftwareInstallationContracts.DataModels;
+using SoftwareInstallationContracts.Exceptions;
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace SoftwareInstallationTests.DataModelsTests;
+
+[TestFixture]
+internal class InstallationSoftwareDataModelTests
+{
+    private InstallationSoftwareDataModel installSoftware;
+
+    [Test]
+    public void InstallIdIsNullOrEmptyTest()
+    {
+        installSoftware = CreateDataModel(null, Guid.NewGuid().ToString(), 10);
+        Assert.That(() => installSoftware.Validate(), Throws.TypeOf<ValidationFieldException>());
+        installSoftware = CreateDataModel(string.Empty, Guid.NewGuid().ToString(), 10);
+        Assert.That(() => installSoftware.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void InstallIdIsNotGuidTest()
+    {
+        installSoftware = CreateDataModel("installId", Guid.NewGuid().ToString(), 10);
+        Assert.That(() => installSoftware.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void SoftwareIdIsNullOrEmptyTest()
+    {
+        installSoftware = CreateDataModel(Guid.NewGuid().ToString(), null, 10);
+        Assert.That(() => installSoftware.Validate(), Throws.TypeOf<ValidationFieldException>());
+        installSoftware = CreateDataModel(string.Empty, Guid.NewGuid().ToString(), 10);
+        Assert.That(() => installSoftware.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void SoftwareIdIsNotGuidTest()
+    {
+        installSoftware = CreateDataModel(Guid.NewGuid().ToString(), "softwareId", 10);
+        Assert.That(() => installSoftware.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void CountIsLessOrZeroTest()
+    {
+        installSoftware = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), 0);
+        Assert.That(() => installSoftware.Validate(), Throws.TypeOf<ValidationFieldException>());
+        installSoftware = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), -10);
+        Assert.That(() => installSoftware.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void AllFieldsIsCorrectTest()
+    {
+        string installId = Guid.NewGuid().ToString();
+        string softwareId = Guid.NewGuid().ToString();
+        int count = 10;
+        installSoftware = CreateDataModel(installId, softwareId, count);
+        Assert.That(() => installSoftware.Validate(), Throws.Nothing);
+        Assert.Multiple(() =>
+        {
+            Assert.That(installSoftware.InstallationId, Is.EqualTo(installId));
+            Assert.That(installSoftware.ProgramId, Is.EqualTo(softwareId));
+            Assert.That(installSoftware.Count, Is.EqualTo(count));
+        });
+    }
+
+    private static InstallationSoftwareDataModel CreateDataModel(string? installId, string? softwareId, int count) =>
+        new(installId, softwareId, count);
+}
diff --git a/SoftwareInstallationTests/DataModelsTests/PostDataModelTests.cs b/SoftwareInstallationTests/DataModelsTests/PostDataModelTests.cs
new file mode 100644
index 0000000..a780697
--- /dev/null
+++ b/SoftwareInstallationTests/DataModelsTests/PostDataModelTests.cs
@@ -0,0 +1,101 @@
+using SoftwareInstallationContracts.DataModels;
+using SoftwareInstallationContracts.Exceptions;
+using SoftwareInstallationContracts.Enums;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace SoftwareInstallationTests.DataModelsTests;
+
+[TestFixture]
+internal class PostDataModelTests
+{
+    private PostDataModel post;
+
+    [Test]
+    public void idIsNotNullOrEmpty()
+    {
+        post = CreateDataModel(null, Guid.NewGuid().ToString(), "name", PostType.Stuff, 10, true, DateTime.UtcNow);
+        Assert.That(() => post.Validate(), Throws.TypeOf<ValidationFieldException>());
+        post = CreateDataModel(string.Empty, Guid.NewGuid().ToString(), "name", PostType.Stuff, 10, true, DateTime.UtcNow);
+        Assert.That(() => post.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void IdIsNotGuidTest()
+    {
+        post = CreateDataModel("id", Guid.NewGuid().ToString(), "name", PostType.Stuff, 10, true, DateTime.UtcNow);
+        Assert.That(() => post.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void PostIdIsNullEmptyTest()
+    {
+        post = CreateDataModel(Guid.NewGuid().ToString(), null, "name", PostType.Stuff, 10, true, DateTime.UtcNow);
+        Assert.That(() => post.Validate(), Throws.TypeOf<ValidationFieldException>());
+        post = CreateDataModel(Guid.NewGuid().ToString(), string.Empty, "name", PostType.Stuff, 10, true, DateTime.UtcNow);
+        Assert.That(() => post.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void PostIdIsNotGuidTest()
+    {
+        post = CreateDataModel(Guid.NewGuid().ToString(), "postId", "name", PostType.Stuff, 10, true, DateTime.UtcNow);
+        Assert.That(() => post.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void SalaryIsLessOrZeroTest()
+    {
+        post = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), "name", PostType.Stuff, 0, true, DateTime.UtcNow);
+        Assert.That(() => post.Validate(), Throws.TypeOf<ValidationFieldException>());
+        post = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), "name", PostType.Stuff, -10, true, DateTime.UtcNow);
+        Assert.That(() => post.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void PostTypeIsNoneTest()
+    {
+        post = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), "name", PostType.None, 10, true, DateTime.UtcNow);
+        Assert.That(() => post.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void PostNameIsEmptyTest()
+    {
+        post = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), null, PostType.Stuff, 10, true, DateTime.UtcNow);
+        Assert.That(() => post.Validate(), Throws.TypeOf<ValidationFieldException>());
+        post = CreateDataModel(Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), string.Empty, PostType.Stuff, 10, true, DateTime.UtcNow);
+        Assert.That(() => post.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void AllFieldsIsCorrectTest()
+    {
+        string postId = Guid.NewGuid().ToString();
+        string postPostId = Guid.NewGuid().ToString();
+        string postName = "name";
+        PostType postType = PostType.Stuff;
+        double salary = 10;
+        bool isActual = false;
+        DateTime changeDate = DateTime.UtcNow.AddDays(-1);
+        post = CreateDataModel(postId, postPostId, postName, postType, salary, isActual, changeDate);
+        Assert.That(() => post.Validate(), Throws.Nothing);
+        Assert.Multiple(() =>
+        {
+            Assert.That(post.Id, Is.EqualTo(postId));
+            Assert.That(post.PostId, Is.EqualTo(postPostId));
+            Assert.That(post.PostName, Is.EqualTo(postName));
+            Assert.That(post.PostType, Is.EqualTo(postType));
+            Assert.That(post.Salary, Is.EqualTo(salary));
+            Assert.That(post.IsActual, Is.EqualTo(isActual));
+            Assert.That(post.ChangeDate, Is.EqualTo(changeDate));
+        });
+    }
+
+    private static PostDataModel CreateDataModel(string? id, string? postId, string? postName,
+        PostType postType, double salary, bool isActual, DateTime changeDate) =>
+        new(id, postId, postName, postType, salary, isActual, changeDate);
+}
diff --git a/SoftwareInstallationTests/DataModelsTests/SalaryDataModelTests.cs b/SoftwareInstallationTests/DataModelsTests/SalaryDataModelTests.cs
new file mode 100644
index 0000000..a57f26d
--- /dev/null
+++ b/SoftwareInstallationTests/DataModelsTests/SalaryDataModelTests.cs
@@ -0,0 +1,60 @@
+using SoftwareInstallationContracts.DataModels;
+using SoftwareInstallationContracts.Exceptions;
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace SoftwareInstallationTests.DataModelsTests;
+
+[TestFixture]
+internal class SalaryDataModelTests
+{
+    private SalaryDataModel salary;
+
+    [Test]
+    public void WorkerIdIsEmptyTest()
+    {
+        salary = CreateDataModel(null, DateTime.Now, 10);
+        Assert.That(() => salary.Validate(), Throws.TypeOf<ValidationFieldException>());
+        salary = CreateDataModel(string.Empty, DateTime.Now, 10);
+        Assert.That(() => salary.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void WorkerIdIsNotGuidTest()
+    {
+        salary = CreateDataModel("workerId", DateTime.Now, 10);
+        Assert.That(() => salary.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void PriceIsLessOrZeroTest()
+    {
+        salary = CreateDataModel(Guid.NewGuid().ToString(), DateTime.Now, 0);
+        Assert.That(() => salary.Validate(), Throws.TypeOf<ValidationFieldException>());
+        salary = CreateDataModel(Guid.NewGuid().ToString(), DateTime.Now, -10);
+        Assert.That(() => salary.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void AllFieldsIsCorrectTest()
+    {
+        string workerId = Guid.NewGuid().ToString();
+        DateTime salaryDate = DateTime.Now.AddDays(-3).AddMinutes(-5);
+        double workerSalary = 10;
+        SalaryDataModel salary = CreateDataModel(workerId, salaryDate, workerSalary);
+        Assert.That(() => salary.Validate(), Throws.Nothing);
+        Assert.Multiple(() =>
+        {
+            Assert.That(salary.WorkerId, Is.EqualTo(workerId));
+            Assert.That(salary.SalaryDate, Is.EqualTo(salaryDate));
+            Assert.That(salary.Salary, Is.EqualTo(workerSalary));
+        });
+    }
+
+    private static SalaryDataModel CreateDataModel(string? workerId, DateTime salaryDate,
+        double workerSalary) => new(workerId, salaryDate, workerSalary);
+}
diff --git a/SoftwareInstallationTests/DataModelsTests/SoftwareDataModelTests.cs b/SoftwareInstallationTests/DataModelsTests/SoftwareDataModelTests.cs
new file mode 100644
index 0000000..fb43cab
--- /dev/null
+++ b/SoftwareInstallationTests/DataModelsTests/SoftwareDataModelTests.cs
@@ -0,0 +1,100 @@
+using SoftwareInstallationContracts.DataModels;
+using SoftwareInstallationContracts.Enums;
+using SoftwareInstallationContracts.Exceptions;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using static NUnit.Framework.Internal.OSPlatform;
+
+namespace SoftwareInstallationTests.DataModelsTests;
+
+[TestFixture]
+internal class SoftwareDataModelTests
+{
+    private SoftwareDataModel software;
+
+    [Test]
+    public void IdIsNullOrEmptyTest()
+    {
+        software = CreateDataModel(null, "name", SoftwareType.ApplicationSoftware, Guid.NewGuid().ToString(), 10, false);
+        Assert.That(() => software.Validate(), Throws.TypeOf<ValidationFieldException>());
+        software = CreateDataModel(string.Empty, "name", SoftwareType.ApplicationSoftware, Guid.NewGuid().ToString(), 10, false);
+        Assert.That(() => software.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void IdIsNotGuidTest()
+    {
+        software = CreateDataModel("id", "name", SoftwareType.ApplicationSoftware, Guid.NewGuid().ToString(), 10, false);
+        Assert.That(() => software.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void SoftwareNameIsEmptyTest()
+    {
+        software = CreateDataModel(Guid.NewGuid().ToString(), null, SoftwareType.ApplicationSoftware, Guid.NewGuid().ToString(), 10, false);
+        Assert.That(() => software.Validate(), Throws.TypeOf<ValidationFieldException>());
+        software = CreateDataModel(Guid.NewGuid().ToString(), string.Empty, SoftwareType.ApplicationSoftware, Guid.NewGuid().ToString(), 10, false);
+        Assert.That(() => software.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void SoftwareTypeIsNoneTest()
+    {
+        software = CreateDataModel(Guid.NewGuid().ToString(), "name", SoftwareType.None, Guid.NewGuid().ToString(), 10, false);
+        Assert.That(() => software.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void CompanyIdIsNullOrEmptyTest()
+    {
+        software = CreateDataModel(Guid.NewGuid().ToString(), "name", SoftwareType.ApplicationSoftware, null, 10, false);
+        Assert.That(() => software.Validate(), Throws.TypeOf<ValidationFieldException>());
+        software = CreateDataModel(Guid.NewGuid().ToString(), "name", SoftwareType.ApplicationSoftware, string.Empty, 10, false);
+        Assert.That(() => software.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void CompanyIdIsNotGuidTest()
+    {
+        software = CreateDataModel(Guid.NewGuid().ToString(), "name", SoftwareType.ApplicationSoftware, "companyId", 10, false);
+        Assert.That(() => software.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void PriceIsLessOrZeroTest()
+    {
+        software = CreateDataModel(Guid.NewGuid().ToString(), "name", SoftwareType.ApplicationSoftware, Guid.NewGuid().ToString(), 0, false);
+        Assert.That(() => software.Validate(), Throws.TypeOf<ValidationFieldException>());
+        software = CreateDataModel(Guid.NewGuid().ToString(), "name", SoftwareType.ApplicationSoftware, Guid.NewGuid().ToString(), -10, false);
+        Assert.That(() => software.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void AllFieldsIsCorrectTest()
+    {
+        string softwareId = Guid.NewGuid().ToString();
+        string softwareName = "name";
+        SoftwareType softwareType = SoftwareType.ApplicationSoftware;
+        string softwareCompanyId = Guid.NewGuid().ToString();
+        double softwarePrice = 10;
+        bool softwareIsDelete = false;
+        SoftwareDataModel software = CreateDataModel(softwareId, softwareName, softwareType, softwareCompanyId, softwarePrice, softwareIsDelete);
+        Assert.That(() => software.Validate(), Throws.Nothing);
+        Assert.Multiple(() =>
+        {
+            Assert.That(software.Id, Is.EqualTo(softwareId));
+            Assert.That(software.SoftwareName, Is.EqualTo(softwareName));
+            Assert.That(software.SoftwareType, Is.EqualTo(softwareType));
+            Assert.That(software.CompanyId, Is.EqualTo(softwareCompanyId));
+            Assert.That(software.Price, Is.EqualTo(softwarePrice));
+            Assert.That(software.IsDeleted, Is.EqualTo(softwareIsDelete));
+        });
+    }
+
+    private static SoftwareDataModel CreateDataModel(string? id, string? softwareName, SoftwareType softwareType,
+        string? companyId, double price, bool isDeleted) => 
+        new(id, softwareName, softwareType, companyId, price, isDeleted);
+}
diff --git a/SoftwareInstallationTests/DataModelsTests/SoftwareHistoryDataModelTests.cs b/SoftwareInstallationTests/DataModelsTests/SoftwareHistoryDataModelTests.cs
new file mode 100644
index 0000000..c24c97c
--- /dev/null
+++ b/SoftwareInstallationTests/DataModelsTests/SoftwareHistoryDataModelTests.cs
@@ -0,0 +1,61 @@
+using SoftwareInstallationContracts.DataModels;
+using SoftwareInstallationContracts.Exceptions;
+using SoftwareInstallationContracts.Enums;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace SoftwareInstallationTests.DataModelsTests;
+
+[TestFixture]
+internal class SoftwareHistoryDataModelTests
+{
+    private SoftwareHistoryDataModel programHistory;
+
+    [Test]
+    public void programHistoryIdIsNullOrEmptyTest()
+    {
+        programHistory = CreateDataModel(null, 10);
+        Assert.That(() => programHistory.Validate(), Throws.TypeOf<ValidationFieldException>());
+        programHistory = CreateDataModel(string.Empty, 10);
+        Assert.That(() => programHistory.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void programHistoryIdIsNotGuidTest()
+    {
+        programHistory = CreateDataModel("id", 10);
+        Assert.That(() => programHistory.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void OldPriceIsLessOrZeroTest()
+    {
+        programHistory = CreateDataModel(Guid.NewGuid().ToString(), 0);
+        Assert.That(() => programHistory.Validate(), Throws.TypeOf<ValidationFieldException>());
+        programHistory = CreateDataModel(Guid.NewGuid().ToString(), -10);
+        Assert.That(() => programHistory.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void AllFieldsIsCorrectTest()
+    {
+        string programHistoryId = Guid.NewGuid().ToString();
+        double oldPrice = 10;
+        programHistory = CreateDataModel(programHistoryId, oldPrice);
+        Assert.That(() => programHistory.Validate(), Throws.Nothing);
+        Assert.Multiple(() =>
+        {
+            Assert.That(programHistory.SoftwareId, Is.EqualTo(programHistoryId));
+            Assert.That(programHistory.OldPrice, Is.EqualTo(oldPrice));
+            Assert.That(programHistory.ChangeDate, Is.LessThan(DateTime.UtcNow));
+            Assert.That(programHistory.ChangeDate, Is.GreaterThan(DateTime.UtcNow.AddMinutes(-1)));
+        });
+    }
+
+
+    private static SoftwareHistoryDataModel CreateDataModel(string? programHistoryId, double oldPrice) =>
+        new(programHistoryId, oldPrice);
+}
diff --git a/SoftwareInstallationTests/DataModelsTests/WorkerDataModelTests.cs b/SoftwareInstallationTests/DataModelsTests/WorkerDataModelTests.cs
new file mode 100644
index 0000000..6ddc839
--- /dev/null
+++ b/SoftwareInstallationTests/DataModelsTests/WorkerDataModelTests.cs
@@ -0,0 +1,100 @@
+using SoftwareInstallationContracts.DataModels;
+using SoftwareInstallationContracts.Exceptions;
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace SoftwareInstallationTests.DataModelsTests;
+
+[TestFixture]
+internal class WorkerDataModelTests
+{
+    private WorkerDataModel worker;
+
+    [Test]
+    public void IdIsNullOrEmptyTest()
+    {
+        worker = CreateDataModel(null, "fio", Guid.NewGuid().ToString(), DateTime.Now.AddYears(-18), DateTime.Now, false);
+        Assert.That(() => worker.Validate(), Throws.TypeOf<ValidationFieldException>());
+        worker = CreateDataModel(string.Empty, "fio", Guid.NewGuid().ToString(), DateTime.Now.AddYears(-18), DateTime.Now, false);
+        Assert.That(() => worker.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void IdIsNotGuidTest()
+    {
+        worker = CreateDataModel("id", "fio", Guid.NewGuid().ToString(), DateTime.Now.AddYears(-18), DateTime.Now, false);
+        Assert.That(() => worker.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void FIOIsNullOrEmptyTest()
+    {
+        worker = CreateDataModel(Guid.NewGuid().ToString(), null, Guid.NewGuid().ToString(), DateTime.Now.AddYears(-18), DateTime.Now, false);
+        Assert.That(() => worker.Validate(), Throws.TypeOf<ValidationFieldException>());
+        worker = CreateDataModel(Guid.NewGuid().ToString(), string.Empty, Guid.NewGuid().ToString(), DateTime.Now.AddYears(-18), DateTime.Now, false);
+        Assert.That(() => worker.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void PostIdIsNullOrEmptyTest()
+    {
+        worker = CreateDataModel(Guid.NewGuid().ToString(), "fio", null, DateTime.Now.AddYears(-18), DateTime.Now, false);
+        Assert.That(() => worker.Validate(), Throws.TypeOf<ValidationFieldException>());
+        worker = CreateDataModel(Guid.NewGuid().ToString(), "fio", string.Empty, DateTime.Now.AddYears(-18), DateTime.Now, false);
+        Assert.That(() => worker.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void PostIdIsNotGuidTest()
+    {
+        worker = CreateDataModel(Guid.NewGuid().ToString(), "fio", "postId", DateTime.Now.AddYears(-18), DateTime.Now, false);
+        Assert.That(() => worker.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void BirthDateIsNotCorrectTest()
+    {
+        worker = CreateDataModel(Guid.NewGuid().ToString(), "fio", Guid.NewGuid().ToString(), DateTime.Now.AddYears(-16).AddDays(1), DateTime.Now, false);
+        Assert.That(() => worker.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void BirthDateAndEmploymentDateIsNotCorrectTest()
+    {
+        worker = CreateDataModel(Guid.NewGuid().ToString(), "fio", Guid.NewGuid().ToString(), DateTime.Now.AddYears(-18), DateTime.Now.AddYears(-18).AddDays(-1), false);
+        Assert.That(() => worker.Validate(), Throws.TypeOf<ValidationFieldException>());
+        worker = CreateDataModel(Guid.NewGuid().ToString(), "fio", Guid.NewGuid().ToString(), DateTime.Now.AddYears(-18), DateTime.Now.AddYears(-16), false);
+        Assert.That(() => worker.Validate(), Throws.TypeOf<ValidationFieldException>());
+    }
+
+    [Test]
+    public void AllFieldsIsCorrectTest()
+    {
+        string workerId = Guid.NewGuid().ToString();
+        string fio = "vasiliy vasilievich";
+        string postId = Guid.NewGuid().ToString();
+        DateTime birthDate = DateTime.Now.AddYears(-16).AddDays(-1);
+        DateTime employmentDate = DateTime.Now;
+        bool isDelete = false;
+        worker = CreateDataModel(workerId, fio, postId, birthDate, employmentDate, isDelete);
+        Assert.That(() => worker.Validate(), Throws.Nothing);
+        Assert.Multiple(() =>
+        {
+            Assert.That(worker.Id, Is.EqualTo(workerId));
+            Assert.That(worker.FIO, Is.EqualTo(fio));
+            Assert.That(worker.PostId, Is.EqualTo(postId));
+            Assert.That(worker.BirthDate, Is.EqualTo(birthDate));
+            Assert.That(worker.EmploymentDate, Is.EqualTo(employmentDate));
+            Assert.That(worker.IsDeleted, Is.EqualTo(isDelete));
+        });
+    }
+
+
+    private static WorkerDataModel CreateDataModel(string? id, string? fio, string? postId, DateTime birthDate,
+        DateTime employmentDate, bool isDeleted) =>
+    new(id, fio, postId, birthDate, employmentDate, isDeleted);
+}
diff --git a/SoftwareInstallationTests/SoftwareInstallationTests.csproj b/SoftwareInstallationTests/SoftwareInstallationTests.csproj
new file mode 100644
index 0000000..561fc18
--- /dev/null
+++ b/SoftwareInstallationTests/SoftwareInstallationTests.csproj
@@ -0,0 +1,27 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net9.0</TargetFramework>
+    <LangVersion>latest</LangVersion>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="coverlet.collector" Version="6.0.2" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
+    <PackageReference Include="NUnit" Version="4.2.2" />
+    <PackageReference Include="NUnit.Analyzers" Version="4.3.0" />
+    <PackageReference Include="NUnit3TestAdapter" Version="4.6.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\SoftwareInstallationContracts\SoftwareInstallationContracts\SoftwareInstallationContracts.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Using Include="NUnit.Framework" />
+  </ItemGroup>
+
+</Project>
diff --git a/SoftwareInstallationTests/SoftwareInstallationTests/DataModelsTests/ClientDataModelTests.cs b/SoftwareInstallationTests/SoftwareInstallationTests/DataModelsTests/ClientDataModelTests.cs
index 98aa58a..5fee08f 100644
--- a/SoftwareInstallationTests/SoftwareInstallationTests/DataModelsTests/ClientDataModelTests.cs
+++ b/SoftwareInstallationTests/SoftwareInstallationTests/DataModelsTests/ClientDataModelTests.cs
@@ -16,48 +16,48 @@ internal class ClientDataModelTests
     [Test]
     public void IdIsNullOrEmptyTest()
     {
-        client = CreateDataModel(null, "fio", "number");
+        client = CreateDataModel(null, "fio", "+7-777-777-77-77");
         Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
-        client = CreateDataModel(string.Empty, "fio", "number");
+        client = CreateDataModel(string.Empty, "fio", "+7-777-777-77-77");
         Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
     }
 
     [Test]
     public void IdIsNotGuidTest()
     {
-        client = CreateDataModel("id", "fio", "number");
+        client = CreateDataModel("id", "Fio Fio Fio", "+7-777-777-77-77");
         Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
     }
 
     [Test]
     public void FIOIsNullOrEmptyTest()
     {
-        client = CreateDataModel(Guid.NewGuid().ToString(), null, "number");
+        client = CreateDataModel(Guid.NewGuid().ToString(), null, "+7-777-777-77-77");
         Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
-        client = CreateDataModel(Guid.NewGuid().ToString(), string.Empty, "number");
+        client = CreateDataModel(Guid.NewGuid().ToString(), string.Empty, "+7-777-777-77-77");
         Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
     }
 
     [Test]
     public void FIOIsIncorrectTest()
     {
-        client = CreateDataModel(Guid.NewGuid().ToString(), "fio", "number");
+        client = CreateDataModel(Guid.NewGuid().ToString(), "fio", "+7-777-777-77-77");
         Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
     }
 
     [Test]
     public void PhoneNumberIsNullOrEmptyTest()
     {
-        client = CreateDataModel(Guid.NewGuid().ToString(), "fio", null);
+        client = CreateDataModel(Guid.NewGuid().ToString(), "Fio Fio Fio", null);
         Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
-        client = CreateDataModel(Guid.NewGuid().ToString(), "fio", string.Empty);
+        client = CreateDataModel(Guid.NewGuid().ToString(), "Fio Fio Fio", string.Empty);
         Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
     }
 
     [Test]
     public void PhoneNumberIsIncorrectTest()
     {
-        client = CreateDataModel(Guid.NewGuid().ToString(), "fio", "777");
+        client = CreateDataModel(Guid.NewGuid().ToString(), "Fio Fio Fio", "777");
         Assert.That(() => client.Validate(), Throws.TypeOf<ValidationFieldException>());
     }
 
@@ -65,7 +65,7 @@ internal class ClientDataModelTests
     public void AllFieldsIsCorrectTest()
     {
         string phoneNumber = "+7-777-777-77-77";
-        string fio = "Василий Васильевич Васильев";
+        string fio = "Vasiliy Vasiliev Vasilievich";
         string id = Guid.NewGuid().ToString();
         client = CreateDataModel(id, fio, phoneNumber);
         Assert.That(() => client.Validate(), Throws.Nothing);
diff --git a/SoftwareInstallationTests/SoftwareInstallationTests/DataModelsTests/InstallationSoftwareDataModelTests.cs b/SoftwareInstallationTests/SoftwareInstallationTests/DataModelsTests/InstallationSoftwareDataModelTests.cs
index ca9dd3c..a42fbb5 100644
--- a/SoftwareInstallationTests/SoftwareInstallationTests/DataModelsTests/InstallationSoftwareDataModelTests.cs
+++ b/SoftwareInstallationTests/SoftwareInstallationTests/DataModelsTests/InstallationSoftwareDataModelTests.cs
@@ -64,7 +64,7 @@ internal class InstallationSoftwareDataModelTests
         Assert.That(() => installSoftware.Validate(), Throws.Nothing);
         Assert.Multiple(() =>
         {
-            Assert.That(installSoftware.SaleId, Is.EqualTo(installId));
+            Assert.That(installSoftware.InstallationId, Is.EqualTo(installId));
             Assert.That(installSoftware.ProgramId, Is.EqualTo(softwareId));
             Assert.That(installSoftware.Count, Is.EqualTo(count));
         });