Added tests for selection level

Diligent.WebAPI.Tests/Controllers/SelectionLevelsControllerTests.cs

-using Diligent.WebAPI.Contracts.DTOs.SelectionLevel;
+using Diligent.WebAPI.Contracts.DTOs.Ad;
+using Diligent.WebAPI.Contracts.DTOs.SelectionLevel;
 using Diligent.WebAPI.Contracts.DTOs.SelectionProcess;
 using Diligent.WebAPI.Contracts.Exceptions;
 
 
             (result as OkObjectResult).StatusCode.Should().Be(200);
         }
+
+        [Fact]
+        public async Task GetFilteredLevels_ShouldReturn_200OK_Always()
+        {
+            var levels = new List<SelectionLevelResponseWithDataDto>
+            {
+                new SelectionLevelResponseWithDataDto
+                {
+                    Id = 1,
+                    Name = "HR intervju",
+                    SelectionProcesses = new List<SelectionProcessResposneDto>()
+                }
+            };
+            var filter = new SelectionProcessFilterDto();
+            _service.GetAllAsync().Returns(levels);
+            SelectionLevelsController controller = new(_service);
+
+            var result = await controller.GetFilteredLevels(filter);
+
+            (result as OkObjectResult).StatusCode.Should().Be(200);
+        }
     }
 }

Diligent.WebAPI.Tests/Services/SelectionLevelsServiceTests.cs

 
             await Assert.ThrowsAsync<EntityNotFoundException>(async () => await service.GetByIdAsync(1000));
         }
+
+        [Fact]
+        public async Task GetByIdEntity_ShouldReturnLevel_WhenLevelExist()
+        {
+            var databaseContext = await Helpers<SelectionLevel>.GetDatabaseContext(_levels);
+            SelectionLevelService service = new(databaseContext, _mapper, _logger);
+
+            var result = await service.GetByIdEntity(1);
+
+            result.Id.Should().Be(_selectionLevel.Id);
+            result.Name.Should().Be(_selectionLevel.Name);
+        }
+        [Fact]
+        public async Task GetByIdEntity_ShouldThrowEntityNotFooundException_WhenLevelDoesnotExist()
+        {
+            var databaseContext = await Helpers<SelectionLevel>.GetDatabaseContext(_levels);
+            SelectionLevelService service = new(databaseContext, _mapper, _logger);
+
+            await Assert.ThrowsAsync<EntityNotFoundException>(async () => await service.GetByIdEntity(1000));
+        }
     }
 }