public void GetAll_IsCorrect()
        {
            //arrange
            IEnumerable <ProductDto> expected = new ProductDto[]
            {
                new ProductDto {
                    ProductId = 2, Name = "2"
                },
                new ProductDto {
                    ProductId = 3, Name = "3"
                }
            };
            Mock <IProductRepository> mock = new Mock <IProductRepository>();

            mock.Setup(p => p.Get())
            .Returns((new Product[] {
                new Product {
                    ProductId = 2, Name = "2"
                },
                new Product {
                    ProductId = 3, Name = "3"
                }
            }).AsQueryable());
            //act
            ProductService           productService = new ProductService(_mapper, mock.Object);
            IEnumerable <ProductDto> actual         = productService.GetAll();

            //assert
            Assert.Equal(expected.Count(), actual.Count());
            mock.Verify(p => p.Get(), Times.Once);
        }