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); }