public async Task UpdateLessonAsync() { //Arrange Theme theme = new Theme { Name = "ExampleName", Id = 5 }; Mentor mentor = new Mentor { Id = 2 }; StudentGroup studentGroup = new StudentGroup { Id = 3 }; List <VisitDto> visitsDto = new List <VisitDto>() { }; var foundLesson = new Lesson() { Id = 7, MentorId = 2, StudentGroupId = 3, ThemeId = 5, Mentor = mentor, StudentGroup = studentGroup, Theme = theme, Visits = { } }; var updateLessonDto = new UpdateLessonDto { ThemeName = null, LessonDate = DateTime.Parse("2020-11-18T15:30:00.384Z"), LessonVisits = null }; var foundLessonDto = new LessonDto() { Id = 7, ThemeName = "ExampleName", MentorId = 2, StudentGroupId = 3, LessonDate = DateTime.Parse("2020-11-18T15:00:00.384Z"), LessonVisits = null }; var updatedLesson = new LessonDto() { Id = 7, ThemeName = "ExampleName", MentorId = 2, StudentGroupId = 3, LessonDate = DateTime.Parse("2020-11-18T15:30:00.384Z"), LessonVisits = visitsDto }; _unitOfWorkMock.Setup(x => x.LessonRepository.GetByIdAsync(7)) .ReturnsAsync(foundLesson); var lessonService = new LessonService( _unitOfWorkMock.Object, _mapper ); //Act var result = await lessonService.UpdateLessonAsync(7, updateLessonDto); //Assert Assert.NotNull(result); Assert.Equal(updatedLesson.Id, result.Id); Assert.Equal(updatedLesson.LessonDate, result.LessonDate); Assert.Equal(updatedLesson.LessonVisits, result.LessonVisits); Assert.Equal(updatedLesson.MentorId, result.MentorId); Assert.Equal(updatedLesson.StudentGroupId, result.StudentGroupId); Assert.Equal(updatedLesson.ThemeName, result.ThemeName); }