[Python-Dev] Allowing to run certain regression tests in subprocesses

[Nick Coghlan]

On 4 Aug 2013 09:43, "Eli Bendersky" <eliben at gmail.com> wrote:
>
> Hi All,
>
> Today the issue of cross-test global env dependencies showed its ugly
> head again for me. I recall a previous discussion
> (http://mail.python.org/pipermail/python-dev/2013-January/123409.html)
> but there were many more over the years.
>
> The core problem is that some tests modify the global env
> (particularly importing modules) and this sometimes has adverse
> effects on other tests, because test.regrtest runs all tests in a
> single process. In the discussion linked above, the particular culprit
> test__all__ was judged as a candidate to be moved to a subprocess.
>
> I want to propose adding a capability to our test harness to run
> specific tests in subprocesses. Each test will have some simple way of
> asking to be run in a subprocess, and regrtest will concur (even when
> running -j1). test__all__ can go there, and it can help solve other
> problems.
>
> My particular case is trying to write a test for
> http://bugs.python.org/issue14988 - wherein I have to simulate a
> situation of non-existent pyexpat. It's not hard to write a test for
> it, but when run in tandem with other tests (where C extensions loaded
> pyexpat) it becomes seemingly impossible to set up. This should not be
> the case - there's nothing wrong with wanting to simulate this case,
> and there's nothing wrong in Python and the stdlib - it's purely an
> artifact of the way our regression suite works.

I'm not actively opposed to the suggested idea, but is there a specific
reason "test.support.import_fresh_module" doesn't work for this test?

Cheers,
Nick.

>
> Thoughts?
>
> Eli
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