Improve Trial's --temp-directory option

[thijs]

Trial should drop a marker file into _trial_temp and refuse to delete and re-create any directory that doesn't have the marker. Docs should updated as well, see #2589

[moonfallen]

Yes, let's do this please. Just had my source directory deleted. Didn't lose anything important, fortunately.

[glyph]

The patch is great! Could you make a few small adjustments?

1. In your test case, the name "my_runner" violates the coding standard. It should be "myRunner".
2. In _removeSafely's docstring (thanks for adding that!) you should probably use L{} rather than C{} to refer to NoTrialMarker.
3. I realize that trial is a pile of bad examples as far as this particular request goes, but could you use twisted.python.filepath.FilePath rather than os.path for path inspection and manipulation? As a bonus (although this is not required) you could remove the dependence on the shutil module, since FilePath handles recursive removal itself.
4. NoTrialMarker's docstring could be more expository. Especially, why is this exception raised? When does trial look for a marker?
5. Also, you might want to follow the example of _WorkingDirectoryBusy and make the exception private, since the only method that raises it is also private. It's always easy to make private stuff public later, less easy to decide it was a bad idea and make it private.

[jonathanj]

3. I've changed _setUpTestdir and _removeSafely to use FilePath internally.

Everything else you said made sense, and I've addressed those changes too.

[thijs]

(In [26970]) Branching to 'trial-tmp-marker-3481'

[thijs]

(In [26972]) Update copyright, refs #3481

[thijs]

Buildbot is  happy, looks ready to merge for me.

If this hits the trunk before #2589 does, then that one should be closed, or marked as fixed with the merge of this ticket. #2589 was created to add a warning to trial's commandline options, but I don't think we need to add more docs than that.

[glyph]

Erm... did you review this, or not? If so, then it should be reassigned to jonathanj, not me. If not, and you're looking for more feedback from me (although I don't see the question) as the reviewer of a non-committer contribution, you should merge it on behalf of jonathanj :).

[glyph]

Gah, that comment was badly garbled. What I meant was:

If you reviewed this, you should be merging it on behalf of jonathanj.

If you just looked at it and gave it a positive comment, but wanted feedback from me, then you should be leaving the review keyword as you reassign it to me.

[thijs]

(In [27098]) Merge trial-tmp-marker-3481: Trial now drops a marker file into _trial_temp and refuses to delete and re-create any directory that doesn't have the marker.

Author: jonathanj, thijs Reviewer: glyph Fixes: #3481