print traceback in successResultOf error reporting

[Ying Li]

It currently prints the repr of the Failure, it'd be nice to be able to find out where the Failure occurred.

Also, would be nice to be able to pass optional errors to failureResultOf to check which errors are supposed to have been raised similar to (like assertRaises)

[Ying Li]

(In [37591]) Branching to 'successResultOf-traceback-6377'

[Ying Li]

(In [37598]) Add an optional expected exception type to failureResultOf. refs #6377

[Ying Li]

Forgot to include a refs tag in the commit message in the previous commit:

(In r37595) Include traceback in successResultOf error reporting

[Ying Li]

(In [37599]) Add topfile. refs #6377

[Ying Li]

​build results

The failure thing might be out of scope and perhaps should be broken into a different ticket, but these are pretty tiny changes.

[Tom Prince]

• successResultOf and failureResultOf are supported on python 3, so additional behaviour for them should be tested, and tested succesfully.
• I'd be inclined so say that failureResultOf should take a list of exception types, like Failure.trap, Failure.check, TestCase.assertFailure. (This would incidentally allow you to simply pass the list to Failure.check, rather than 'if x and f.check(x):`.
• The news item would read better as two seperate news items, which suggests that this should be two tickets.

[Ying Li]

(In [37616]) Move failureResultOf changes to a different ticket, and fix python3 tests. refs #6377

[Ying Li]

Thanks for the quick review tom.prince!

1. Hm... ok, I'm now testing to see if the traceback is in the str of the exception, since in Python 3 exceptions don't necessarily have a .message attribute anymore.
2. I've split the failureResultOf stuff into #6380.
3. Changed the newsfile to a .misc instead.

​buildbot results

[Tom Prince]

Looks good, please merge.

[Ying Li]

(In [37828]) Merge successResultOf-traceback-6377: more useful traceback if failure

Author: cyli Reviewer: tom.prince Fixes: #6377

If the Deferred provided to successResultOf errbacks, print a traceback instead of just the repr of the failure.