monkey patching 'debug' breaks twisted.internet.base.DelayedCall

[Jelmer Vernooij]

 affects testtools

twisted.internet.base.DelayedCall has different behaviour depending
whether or not debug was specified to its constructor. It will set
self.creator to traceback.format_stack().

Later on, in its __str__ it uses the debug attribute to determine
whether or not to add a traceback to the output - a traceback which is
not available in case testtools monkey patched debug to be true.

Btw, apart from this issue the debug code was really useful in tracking
down a bug in the builddmanager yesterday. Thanks for writing it.

Cheers,

jelmer

[Jonathan Lange (jml)]

I don't understand this bug. In particular, it's not clear how monkey-patching debug breaks DelayedCall.

It sounds like it might be an issue with DelayedCall itself?

[Jelmer Vernooij (jelmer)]

So, if I understand correctly, the main issue is a bug in twisted, namely that DelayedCall doesn't deal well with its "debug" attribute "changing" after it has been created?

[Jonathan Lange (jml)]

That seems right to me. testtools probably should work around Twisted, and we should probably fix upstream as soon as we can.

[Jonathan Lange (jml)]

This is serious enough that I would like to fix it before adding any features.

 importance: High