使用Moq和MSTest测试异常的正确方法

对于Moq与MsTest的行为有些困惑.

A little confusion as to the behaviour of Moq with MsTest.

这不是如何测试"的问题.或我该如何断言?"，这是查看MoQ的工作原理的便笺簿，因此请不要关注异常类型等.

This is not a question of "How do I test?" or "How do I assert?", this is a scratch pad to see how MoQ works so don't focus on the exception type etc.

我认为一个更好的问题可能是=>"Moq投掷行为是否类似于MsTest ExpectedExceptionAttribute?"也就是说，他们期望测试或SUT中有异常吗?

I think a better question may be => "Does Moq Throws<> behave similar to MsTest ExpectedExceptionAttribute?" That is, they're expecting an exception in the test or the SUT?

我想知道与MsTest一起使用的MoQ"Throws"是如何工作的.最好不使用MsTest预期的异常属性吗?在测试中执行try..catch更好吗?我对此还有其他疑问.

I'd like to know just how MoQ "Throws" works when used with MsTest. Is it better to not use the MsTest expected exception attribute? Is it better to perform a try..catch within the test? I have a few more questions surrounding this.

我正在模拟数据库调用，当发生错误时，我想返回零(0).

I am Mocking a database call and when an error occurs I would like to return zero (0).

TestMethod具有MsTest异常属性，而Moq引发throws异常.仅当我在SaveCart方法中引发异常时才起作用，而当我返回零时则无效.

The TestMethod is straight forward with the MsTest exception attribute, and the throws exception with Moq. It only works when I throw an exception within the SaveCart method and not when I return zero.

我想了解基本行为，因为感觉好像我不应该，也不想在SaveCart方法内引发异常.

I would like to understand the underlying behaviour because it feels as though I shouldn't, nor want to throw an exception within the SaveCart method.

这是正在测试的问题:

[TestMethod]
[ExpectedException(typeof(ApplicationException))]
public void CartRepoSaveCartExceptionShouldReturnZero()
{
     _cartDatabaseMock.Setup(c => c.SaveCart(_cart))
                                   .Throws<ApplicationException>();

    var result = _cartRepository.SaveCart(_cart);

    Assert.AreEqual(result, _cartSaveExceptionValue);
}

这是基本的SaveCart，它不会引发异常而导致测试失败:

Here is the basic SaveCart which does NOT throw an exception causing the test to fail:

public long SaveCart(Cart cart )
{
    long returnValue;

    try
    {
        returnValue = _cartDatabase.SaveCart(cart);
    }
    catch (Exception)
    {
        return 0;
    }
    return returnValue;
}

这是一个基本的SaveCart，测试可以在这里进行，因为它会抛出异常:

Here is a basic SaveCart where the test works because it's throwing an exception:

public long SaveCart(Cart cart )
{
    long returnValue;

    try
    {
        returnValue = _cartDatabase.SaveCart(cart);
    }
    catch (Exception)
    {
        throw new ApplicationException();
    }
    return returnValue;
}

如果对问题的解释不够清楚，可以随意提出一个更好的标题.

Feel free to suggest a better title for the question if it doesn't quite explain it clearly.