From: Gavin Sinclair <gsinclair@...>
Date: 2003-02-07T03:00:35+09:00
Subject: Re: Return values from assertions

On Friday, February 7, 2003, 2:52:38 AM, Matt wrote:

> <nathaniel@NOSPAMtalbott.ws> writes:

>> Matt Armstrong [mailto:matt@lickey.com] wrote:
>>
>>> I've often wondered how useful assert_no_exception actually 
>>> is, given that the framework reports uncaught exceptions anyway.
>>
>> The only advantage I see is if you wanted a particular exception
>> that could be thrown to show up as a failure instead of an
>> error. This can be particularly useful if you want to add an
>> assertion message if/when that exception is thrown.

> That hits the crux of my question -- the only practical difference
> between a failure and an error is that the error can have a nice error
> message?

The conceptual difference is practical enough for me.

Conceptual difference:

  - failure: specifically tested condition that, well, failed
  - error: unexpected, uncaught exception

If you expect that certain code will throw an exception, you test for
it and record a success or failure.  If you don't expect an exception,
and you get one, then either your code or your test is seriously
wrong, in a different kind of way to a failed assertion.

Therefore, failures and errors highlight different problems in the
code, and this is a practical difference.

You probably knew all that and were angling at something else...

Gavin