tests/test-dirs.py

run-tests: stop ignoring venv-installed packages

This will allow test dependencies to be installed within a venv, instead of
tampering with sys/user sites.  One thing to note here is that the `VIRTUAL_ENV`
path takes precedence over system-site, unlike when run directly with an
activated `venv`.  For example, `sys.path` as viewed from a feature test in
`hghave.py`, when running `hghave vcr` directly with an activated `venv`:

    sys.path: [
        '/home/jenkins/hg-committed/tests',
        '/usr/lib/python38.zip',
        '/usr/lib/python3.8',
        '/usr/lib/python3.8/lib-dynload',
        '/home/jenkins/test_venv/lib/python3.8/site-packages'
    ]

vs `sys.path` from the same feature test, when run by `run-tests.py` with this
change:

    sys.path: [
        '/home/jenkins/hg-committed/tests',
        '/home/jenkins/hg-committed',
        '/home/jenkins/hg-committed/tests',
        '/home/jenkins/test_venv/lib/python3.8/site-packages',
        '/usr/lib/python38.zip',
        '/usr/lib/python3.8',
        '/usr/lib/python3.8/lib-dynload',
        '/home/jenkins/.local/lib/python3.8/site-packages',
        '/usr/local/lib/python3.8/dist-packages',
        '/usr/lib/python3/dist-packages'
    ]

import unittest

import silenttestrunner

from mercurial import pathutil


class dirstests(unittest.TestCase):
    def testdirs(self):
        for case, want in [
            (b'a/a/a', [b'a', b'a/a', b'']),
            (b'alpha/beta/gamma', [b'', b'alpha', b'alpha/beta']),
        ]:
            d = pathutil.dirs([])
            d.addpath(case)
            self.assertEqual(sorted(d), sorted(want))

    def testinvalid(self):
        with self.assertRaises(ValueError):
            d = pathutil.dirs([])
            d.addpath(b'a//b')


if __name__ == '__main__':
    silenttestrunner.main(__name__)