[IPython-dev] Dropping our parametric tests system

Brian Granger ellisonbg at gmail.com
Fri Aug 30 18:18:43 EDT 2013

I am fine with this plan.

On Fri, Aug 30, 2013 at 1:38 PM, Thomas Kluyver <takowl at gmail.com> wrote:
> I propose that we get rid of our parametric test system, in favour of either
> writing regular tests, or using nose's test generators.
> The parametric tests have failed to run on at least three occasions:
> - Old versions of nose, which we ended up monkeypatching
> - Again on newer versions of nose with Python 2, which Min's PR #4148 and my
> #4150 fix using monkeypatches
> - On Python 3, it only runs to the first yield, and presumably has done ever
> since we first had a Python 3 port (also addressed in #4150)
> So it fails a lot, and it fails quietly, without any warnings or error
> messages, which is exactly what you don't want for a test suite. You just
> realise one day that lots of tests aren't actually being run. Finally, the
> fixes that we've had to introduce are conceptually horrible, and the
> ParametricTestCase code is fairly complex itself.
> The advantage of parametric tests over conventional tests is mainly that the
> testing output reports a greater number of tests being run, even though it's
> not actually exercising any more code. The advantage over nose test
> generators is that the code is executed in the real context in which you'd
> want to debug it. I don't think that either benefit, and especially the
> benefit over plain tests, is worth the pain this is causing us.
> Min suggested that I write an IPEP for this, but in my opinion this isn't a
> big enough change to require an IPEP. I'm happy to write one if people feel
> I need to, though.
> Thomas
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Brian E. Granger
Cal Poly State University, San Luis Obispo
bgranger at calpoly.edu and ellisonbg at gmail.com

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