Simplify virtualenv test in test_testing

[YannickJadoul]

I'm curious if this will allow us to get rid of the __CIBW_VIRTUALENV_PATH__ environment variable we always set in the test virtualenv, with the only purpose of using it in our tests.

It's not brilliantly documented, but it seems a reasonable assumption and if anything changes in future virtualenv releases, this is much more likely to give false negative detections (and thus fail tests when they should not, rather than vice versa).

See #283

[YannickJadoul]

Ah, yes, if the CI passes: @Czaki, what do you think of this? Could this replace #283, or do you have objections?

[Czaki]

@YannickJadoul I remember that I try with base_prefix, etc and do not find working one. Maybe some upgrades in virtualenv will fix it.

Other option which i see Is that PATH variable is controlled by cibuildwheel. So maybe:

base_path = os.environ.get("PATH").split(os.path.pathsep)[0]

[YannickJadoul]

@YannickJadoul I remember that I try with base_prefix, etc and do not find working one. Maybe some upgrades in virtualenv will fix it.

@Czaki, yup, it seems like it now does work in virtualenv? The only failure is the problem with the PyPy linking (see #371).

Other option which i see Is that PATH variable is controlled by cibuildwheel. So maybe:

base_path = os.environ.get("PATH").split(os.path.pathsep)[0]

No, I think your original solution was better then. Here you're just testing the same as what the code does, so I don't think it would make a great test.

But anyway, now this solution with base_prefix works, do you think we should merge it to replace the old test?

[Czaki]

I think this could be replaced.

[YannickJadoul]

Alright, thanks, @Czaki!

Up to @joerick to check then, but this could be merged.

[joerick]

Nice bit of cleanup! :)