public void GetCartItem_WhenExistingProductIdPassed_ReturnsRightCartItem() { //Arrange var myDbContextMoq = new DbContextMock <ShoppingCartContext>(myDummyOptions); myDbContextMoq.CreateDbSetMock(x => x.CartItems, new[] { new CartItem { ProductId = 1, Price = 3, Quantity = 2 }, new CartItem { ProductId = 2, Price = 2, Quantity = 5 } }); CartItemService service = new CartItemService(myDbContextMoq.Object); //Act var result1 = service.GetCartItem(1); var result2 = service.GetCartItem(2); //Assert Assert.Equal(2, result1.Quantity); Assert.Equal(5, result2.Quantity); }