[Python-Dev] unittest output (original) (raw)

Guido van Rossum guido at python.org
Wed Dec 3 09:09:58 EST 2003

> > When a test fails, it is accompanied by tracebacks that include > > all the processing within the unittest module itself. This makes > > it darned difficult to see at a glance what went wrong. If like > > me, you use unittest as part of the development process, then you > > run it hundreds of times each week and this eyesore gets to be a > > real PITA. > > > > I don't recall when or where, but someone has proposed a fix. > > But, like many great ideas, it got stymied because someone, > > somewhere has a use for the rest of the traceback. Also, a > > developer raised the (IMO red herring) issue -- what if there > > is a bug in the unittest module, how would you track it. > > http://www.python.org/sf/722638

Arghh. I had forgotten that Steve Purcell weighed in on this. It's his module. So unless he can be persuaded, the point is moot :-(

Not so fast.

The patch claims to only suppress the traceback if the test failed (e.g. called self.fail(), or one of the assertXXX variations failed). If the test raised an unexpected exception (unittest calls this an error) the traceback is printed normally. This seems right to me.

A refinement could be to make the output look like a (short) traceback as printed by the traceback module even in the failure case; this would address Steve's issue tht IDEs find lines in the code via the traceback. And there should be a command line switch and an environment variable to show the full traceback in all cases.

I'd also plead for a switch to let unittest not catch exceptions at all -- there are situations where you really want to invoke a debugger.

The IDLE issue is separate; I agree that IDLE should treat SystemExit differently (simply go back to the >>> prompt without printing a traceback, printing the status only if it is true). You should add this to the idlefork SF tracker so Kurt can address it.

--Guido van Rossum (home page: http://www.python.org/~guido/)

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