Добавил проверку на различие пользователей в сущности подписки

nekontakte/src/main/java/com/example/nekontakte/subscribes/api/SubscribeController.java

@@ -4,6 +4,7 @@ import java.util.List;
 
 import com.example.nekontakte.core.configurations.Constants;
 
+import org.apache.coyote.BadRequestException;
 import org.modelmapper.ModelMapper;
 import org.springframework.data.domain.PageRequest;
 import org.springframework.web.bind.annotation.DeleteMapping;
@@ -67,7 +68,7 @@ public class SubscribeController {
     }
 
     @PostMapping
-    public SubscribeDTO create(@RequestBody @Valid SubscribeDTO SubscribeDTO) {
+    public SubscribeDTO create(@RequestBody @Valid SubscribeDTO SubscribeDTO) throws BadRequestException {
         return toDTO(subscribeService.create(toEntity(SubscribeDTO)));
     }
 

nekontakte/src/main/java/com/example/nekontakte/subscribes/service/SubscribeService.java

@@ -4,6 +4,7 @@ import java.util.List;
 
 import java.util.stream.StreamSupport;
 
+import org.apache.coyote.BadRequestException;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.PageRequest;
 import org.springframework.stereotype.Service;
@@ -56,7 +57,10 @@ public class SubscribeService {
         return repository.findById(id).orElseThrow(() -> new NotFoundException(SubscribeEntity.class, id));
     }
 
-    public SubscribeEntity create(SubscribeEntity entity) {
+    public SubscribeEntity create(SubscribeEntity entity) throws BadRequestException {
+        if (entity.getSubscriber().getId() == entity.getUser().getId()) {
+            throw new org.apache.coyote.BadRequestException("User do not subscribe themself");
+        }
         return repository.save(entity);
     }
 

nekontakte/src/test/java/com/example/nekontakte/SubscribeServiceTests.java

@@ -37,7 +37,7 @@ public class SubscribeServiceTests {
         private SubscribeEntity secondSubscribe;
 
         @BeforeEach
-        void createData() throws ParseException {
+        void createData() throws ParseException, BadRequestException {
                 removeData();
                 SimpleDateFormat dateFormatter = new SimpleDateFormat("dd.MM.yyyy", Locale.ENGLISH);