Moq Throws an exception for verify - moq

Question

I'm new to Mocking, but this must be something really basic that I'm missing:
The test code below produces an exception:
Expected invocation on the mock at least once, but was never performed: x => x.DeleteProducts(._products)\r\n\r\nConfigured setups:\r\nx => x.DeleteProducts(._products), Times.Never\r\n\r\nPerformed invocations:\r\nIProductRepository.DeleteProducts(System.Collections.Generic.List`1[WebApiDemo.DataAccessLayer.Product])
I step through the controller method and it does seem to call the DeleteProducts method...
// Arrange
IEnumerable<Product> _products = Helpers.ProductHelpers.CreateProducts(_numberProducts);
Mock<IProductRepository> _productRepository = new Mock<IProductRepository>();
_productRepository.Setup(x => x.DeleteProducts(_products));
ProductsController controller = new ProductsController(_productRepository.Object);
// Act
controller.Destroy(_productViewModels); // Destroy calls DeleteProducts
// Assert
_productRepository.Verify(x => x.DeleteProducts(_products));

Answer 1

Does DeleteProducts(_products); return void? I assume it does, so you need to put the .Verifiable() at the end of the .Setup() for it.
With that in place, it should run through ok, although I'm not sure why you have the Times.Never() instead of Times.Once() ??
I would also advocate on the Setup call using It.IsAny<T> rather than a specific collection, such as:
MyMock.Setup(x => x.MyMethod(It.IsAny<IEnumerable<Widget>>)).Verifiable()

Answer 2

Unless you have the mock behaviour set to strict there is no need for the setup. You are not returning anything from the Delete. The call to Verify will suffice.
Some things are not totally obvious from the code.
The repository deletes products but the controller destroys productviewmodels.
In Moq 4 the test should work if
You have a product view model for every product in _products
The Controller.Destroy method gets products from the viewmodels in the same order as _products
I would check that _productViewModels is a 1:1 match to the _products and check how Destroy() extracts the products from the viewmodels before calling Delete()
I would not go with the IsAny>() because you want to check that these specific products were deleted not any other ones.
[TestClass]
public class Verifying {
public interface IProductRepository {
void Delete(IEnumerable<Product> products);
}
public class ProductController {
private IProductRepository _repository;
public ProductController(IProductRepository repository) {
_repository = repository;
}
public void Destroy(IEnumerable<Product> products) {
_repository.Delete(products);
}
public void Destroy(IEnumerable<ProductViewModel> productViewModels) {
_repository.Delete(productViewModels.Select(vm => vm.Product));
}
}
public class Product {
}
public class ProductViewModel {
public Product Product { get; set;}
}
static Verifying() {
sProducts = new List<Product> { new Product(), new Product(), new Product() };
sProductViewModels = new List<ProductViewModel>(sProducts.Select(p => new ProductViewModel { Product = p }));
}
private static List<Product> sProducts;
private static List<ProductViewModel> sProductViewModels;
private Mock<IProductRepository> _mockRepository;
private ProductController CreateController() {
_mockRepository = new Mock<IProductRepository>();
return new ProductController(_mockRepository.Object);
}
[TestMethod]
public void DestroyingProducts() {
var controller = CreateController();
controller.Destroy(sProducts);
_mockRepository.Verify(mk => mk.Delete(sProducts));
}
[TestMethod]
public void DestroyingProductViewModels() {
var controller = CreateController();
controller.Destroy(sProductViewModels);
_mockRepository.Verify(mk => mk.Delete(sProducts));
}
}