tests/test-dirs.py

dirs: reject consecutive slashes in paths

We shouldn't ever see those, and the fuzzer go really excited that if
it gives us a 65k string with 55k slashes in it we use a lot of RAM.

This is a better fix than what I tried in D7105. It was suggested by
Yuya, and I verified it does in fact cause the fuzzer to not OOM.

This is a revision of D7234, but with the missing set of an error
added. I added a unit test of the dirs behavior because I needed to
reason more carefully about the failure modes around consecutive
slashes.

Differential Revision: https://phab.mercurial-scm.org/D7252

from __future__ import absolute_import

import unittest

import silenttestrunner

from mercurial import util


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 = util.dirs({})
            d.addpath(case)
            self.assertEqual(sorted(d), sorted(want))

    def testinvalid(self):
        with self.assertRaises(ValueError):
            d = util.dirs({})
            d.addpath(b'a//b')


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