public void GetProducts() { //Arrange Mock <IProductRepository> mockProductRepository = new Mock <IProductRepository>(); mockProductRepository.Setup(service => service.GetProducts()) .Returns(new List <Product>() { new Product(), new Product() }); IProductApplicationService productsApplicationService = new ProductApplicationService(mockProductRepository.Object); //Act IList <ProductDto> result = productsApplicationService.GetProducts(); //Assert Assert.IsAssignableFrom <IList <ProductDto> >(result); }