我如何断言C＃异步方法在单元测试中引发异常？

问题描述

我想知道的是如何断言异步方法在C＃单元测试中抛出异常？我可以在Visual Studio 2012中使用 Microsoft.VisualStudio.TestTools.UnitTesting 编写异步单元测试，但还没有弄清楚如何测试异常。我知道xUnit.net也支持这种异步测试方法，虽然我还没有尝试过这个框架。

对于我的意思，代码定义了被测系统：

  using System; 
使用System.Threading.Tasks; 
 
 public class AsyncClass 
 {
 public AsyncClass（）{} 
 
 public Task< int> GetIntAsync（）
 {
 throw new NotImplementedException（）; 
} 
} 
  

此代码段定义了一个测试 TestGetIntAsync for AsyncClass.GetIntAsync 。这是我需要输入如何完成 GetIntAsync 抛出异常的断言：

 使用Microsoft.VisualStudio.TestTools.UnitTesting; 
使用System.Threading.Tasks; 
 
 [TestClass] 
 public class TestAsyncClass 
 {
 [TestMethod] 
 public async任务TestGetIntAsync（）
 {
 var obj = new AsyncClass（）; 
 //如何断言抛出异常？ 
 var rslt = await obj.GetIntAsync（）; 
} 
} 
  

随意使用一些其他相关的单元测试框架Visual Studio一个，如xUnit.net，如果需要，或者你会认为这是一个更好的选择。

解决方案

请尝试标记方法：

  [ExpectedException（typeof（NotImplementedException））] 
  pre> 
What I would like to know is how I can assert that an asynchronous method throws an exception, in a C# unit test? I am able to write asynchronous unit tests with Microsoft.VisualStudio.TestTools.UnitTesting in Visual Studio 2012, but have not figured out how to test for exceptions. I know that xUnit.net also supports asynchronous test methods in this way, although I haven't tried that framework yet.

For an example of what I mean, the following code defines the system under test:
using System;
using System.Threading.Tasks;

public class AsyncClass
{
    public AsyncClass() { }

    public Task<int> GetIntAsync()
    {
        throw new NotImplementedException();
    }
}
This code snippet defines a test TestGetIntAsync for AsyncClass.GetIntAsync. This is where I need input on how to accomplish the assertion that GetIntAsync throws an exception:
using Microsoft.VisualStudio.TestTools.UnitTesting;
using System.Threading.Tasks;

[TestClass]
public class TestAsyncClass
{
    [TestMethod]
    public async Task TestGetIntAsync()
    {
        var obj = new AsyncClass();
        // How do I assert that an exception is thrown?
        var rslt = await obj.GetIntAsync();
    }
}
Feel free to employ some other relevant unit test framework than the Visual Studio one, such as xUnit.net, if necessary or you would argue that it's a better option.
 解决方案 
Please try mark method with:
[ExpectedException(typeof(NotImplementedException))]
                        
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