[Python-Dev] Failures in test_site.py - how to debug? (original) (raw)

Brett Cannon brett at python.org
Fri Aug 19 17:34:17 EDT 2016

On Fri, 19 Aug 2016 at 14:11 Chris Angelico <rosuav at gmail.com> wrote:

On Sat, Aug 20, 2016 at 5:33 AM, Brett Cannon <brett at python.org> wrote: >> Hmmmmmmm. So the question is, what is this test testing? > > > It's making sure people who work on the modules that are imported during > startup don't accidentally add another module dependency to the startup > sequence. Since module imports impact startup time we have historically > worked hard to minimize import dependencies for startup (hence things like > certain functions in the os module doing imports within a function even > though we discourage that practice in general).

Fair enough. Which means it probably should import site, because that's going to happen on all normal usage. So that still leaves a few options: 1) Demand that .pth files restrict themselves to what's already imported. This means startup is still fast even if you have a bunch of pths. Downside: Third-party code can break Python's rules. Upside: When they do, it can be reported as a bug, the fixing of which will improve startup times when that's installed. 2) Change the test to somehow disable .pth execution while keeping the rest of site.py intact. This gives more consistent test results, but still is mostly applicable to normal usage. 3) Ignore the problem and assume that the Python test suite will be run with no site-packages installed. Status quo, basically. Possibly with some tweaks so running 'make test' ignores site-packages? Is #2 doable?

Anything is doable given enough time and effort. ;) As of right now the only way is with -S.

If not, can 'make test' somehow hack out site-packages?

The problem is you're dealing with startup which means it won't come into effect until it's too late. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20160819/29fe70d2/attachment.html>

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