public void GetAllBooks_ReturnsOk() { mockService.Setup(s => s.GetAllBooks()) .Returns(BookTestData.GetAllBooksServiceResponse()); BookController bookController = new BookController(mockService.Object); AddBookDto newBook = BookTestData.AddBookDto(); bookController.AddBook(newBook); var result = bookController.Get(); Assert.That(result, Is.InstanceOf <OkObjectResult>()); }