public void Test_Update_WithNonExistingList()
        {
            //Arrange
            var controller  = new ListsController(listService);
            var updatedList = new ToDoList
            {
                Id    = "3",
                Name  = "Test Code",
                Items = new List <Item> {
                    new Item {
                        Id = 0, Name = "Arrange", IsChecked = true
                    },
                    new Item {
                        Id = 1, Name = "Act", IsChecked = true
                    },
                }
            };

            //Act
            var result = controller.Update(updatedList) as NotFoundResult;

            //Assert
            Assert.IsInstanceOfType(result, typeof(NotFoundResult));
            Assert.AreEqual(result.StatusCode, 404);
            listService.DidNotReceive().Update("3", updatedList);
        }