c# - 单元测试 webapi 异步操作

Question

我是单元测试的新手，但我正在努力了解它以尝试提高我编写的代码的质量。

我创建了一个返回客户的 webapi2 项目

   public async Task<IHttpActionResult> GetCustomer([FromUri]int id)
    {
         var customer = await _repository.FindCustomerAsync(id);
         return Ok(customer);
    }

我的仓库

 public async Task<Customer> FindCustomerAsync(int id)
    {
        using (var context = new MyContext())
        {
            var result = await context.Customers.FindAsync(id);
            return result;    
        }

    }

以前我没有返回异步任务，因为它很容易测试。将操作迁移到异步任务让我很难测试。

我正在使用 Moq 和 Xunit，我的单元测试尝试看起来像

 [Fact()]
    public async void GetCustomer()
    {
        var id = 2;

        _customerMock.Setup(x => x.FindCustomerAsync(id))
            .Returns(Task.FromResult(FakeCustomers()
            .SingleOrDefault(cust => cust.customerID == id)));


        var controller = new CustomersController(_customerMock.Object).GetCustomer(id);
        var result = await controller as Customer;

        Assert.NotNull(result);

        //Assert.IsType<OkNegotiatedContentResult<Customer>>(negotiatedResult);
        //Assert.Equal(negotiatedResult.Content.customerID, id);
    }

我的假客户

  private IQueryable<Customer> FakeCustomers()
    {
        return new List<Customer>()
    {
        new Customer()
        {
            customerID = 1,
            firstName = "Brian",
            lastName = "Smith"
        },
        new Customer()
        {
            customerID = 2,
            firstName = "Tom",
        }
    }.AsQueryable();
    }

当尝试转换为 Customer {"Object reference not set to an instance of an object."时，测试总是失败。}

我的测试做错了什么？

Answer 1

你可以这样试试吗？:

[Fact()]
public async void GetCustomer()
{
    var id = 2;

    _customerMock.Setup(x => x.FindCustomerAsync(id))
        .Returns(Task.FromResult(new Customer()
                 {
                  customerID = 2,
                  firstName = "Tom",
                 }));


    var controller = new CustomersController(_customerMock.Object).GetCustomer(id);
    var result = await controller as Customer;

    Assert.NotNull(result);
}