tests/test-dirs.py

rust-nodemap: accounting for dead blocks

By the very append-only nature of the `NodeTree`, inserting
new blocks has the effect of making some of the older ones
useless as they become unreachable.

Therefore some automatic housekeeping will need to be provided.
This is standard procedure in the word of databases, under names
such as "repack" or "vacuum".

The new `masked_readonly_blocks()` will provide callers with
useful information to decide if the nodetree is ripe for
repacking, but all the `NodeTree` can provide is how many
blocks have been masked in the currently mutable part. Analysing
the readonly part would be way too long to do it for each
transaction and defeat the whole purpose of nodemap persistence.
Serializing callers (from the Python layer) will get this figure
before each extraction and maintain an aggregate counter of
unreachable blocks separately.

Note: at this point, the most efficient repacking is just to restart
afresh with a full rescan.

Differential Revision: https://phab.mercurial-scm.org/D8097

from __future__ import absolute_import

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__)