Created to record the egregious hack of relying on the test_runpy infrastructure in order to test pkgutil.walk_packages.

It gets the job done, but is a really messy way of going about it. Worth cleaning up by factoring the support code out to a helper module when there isn't a release deadline looming.

Also, a second test case should be added to cover the zipimporter.zipimporter component.

Such helper functionality could also be used in the tests of unittest.TestLoader.loadTestsFromName().  See, for example, the tests proposed for issue 7559.

The walk_packages tests should also be enhanced to ensure correctly handling of namespace packages

Note that the problem described in #14787 will limit the scope of what can be tested.

I'd like to work on this if that's okay.  I've already written test cases for issue 7559 and issue 15299 that required creating temporary packages, so I understand the need.  And I'd also like to create test cases for issue 14787, which should really be done after this.

I think this should be split into two parts though: (1) refactor the create-package code in test_runpy into a separate helper module, and (2) move the refactored walk_package tests from test_runpy into test_pkgutil (so it's easier to see what has changed).

I can create a new issue for (1).

That sounds good, and thanks for working on this - if we can get the tests cleaned up for the 3.3 release, that will make ongoing maintenance a lot easier.