public async void FindBookRoute_Test() { // Arrange var newBook = CreateBook(); var genreList = new List <Genre>() { new Genre() { Name = "name 1" } }; _bookRepository .Setup(x => x.Single(It.IsAny <Expression <Func <Book, bool> > >())) .ReturnsAsync(newBook); _bookRepository .Setup(x => x.GetAllRelated <Genre, InGenre>(It.IsAny <Expression <Func <Book, bool> > >(), It.IsAny <Genre>(), It.IsAny <InGenre>())) .ReturnsAsync(genreList); var bookController = new BookController(_bookRepository.Object, _genreRepository.Object, _mapper); // Act var result = await bookController.FindBookAsync(newBook.Id); var okResult = result as OkObjectResult; var returnedBookjson = okResult.Value as string; var returnedBook = JsonSerializer.Deserialize <Book>(returnedBookjson); // Assert Assert.True(okResult != null); Assert.True(returnedBook != null); Assert.Equal(200, okResult.StatusCode); }