tests/hghave

bookmark: add a test for a race condition on push

Bookmark pointing to unknown nodes are ignored. Later these ignored bookmarks
are dropped when writing the file back on disk. On paper, this behavior should
be fine, but with the current implementation, it can lead to unexpected
bookmark deletions.

In theory, to make sure writer as a consistent view, taking the lock also
invalidate bookmark data we already loaded into memory.  However this
invalidation is incomplete. The data are stored in a `filecache` that preserve
them if the bookmark related file are untouched. In practice, the bookmark data
in memory also depends of the changelog content, because of the step checking
if the bookmarks refers to a node known to the changelog. So if the bookmark
data were loaded from an up to date bookmark file but filtered with an outdated
changelog file this go undetected.

This condition is fairly specific, but can occurs very often in practice.  We
introduce a test recreating the situation. The test comes in an independant
changeset to show it actually reproduce the situation. The fix will come soon
after.

A large share of the initial investigation of this race condition was made by
Valentin Gatien-Baron <[e-mail]>.

#!/usr/bin/env python
"""Test the running system for features availability. Exit with zero
if all features are there, non-zero otherwise. If a feature name is
prefixed with "no-", the absence of feature is tested.
"""

from __future__ import absolute_import, print_function

import hghave
import optparse
import os
import sys

checks = hghave.checks

def list_features():
    for name, feature in sorted(checks.items()):
        desc = feature[1]
        print(name + ':', desc)

def test_features():
    failed = 0
    for name, feature in checks.items():
        check, _ = feature
        try:
            check()
        except Exception as e:
            print("feature %s failed:  %s" % (name, e))
            failed += 1
    return failed

parser = optparse.OptionParser("%prog [options] [features]")
parser.add_option("--test-features", action="store_true",
                  help="test available features")
parser.add_option("--list-features", action="store_true",
                  help="list available features")

def _loadaddon():
    if 'TESTDIR' in os.environ:
        # loading from '.' isn't needed, because `hghave` should be
        # running at TESTTMP in this case
        path = os.environ['TESTDIR']
    else:
        path = '.'

    if not os.path.exists(os.path.join(path, 'hghaveaddon.py')):
        return

    sys.path.insert(0, path)
    try:
        import hghaveaddon
        assert hghaveaddon  # silence pyflakes
    except BaseException as inst:
        sys.stderr.write('failed to import hghaveaddon.py from %r: %s\n'
                         % (path, inst))
        sys.exit(2)
    sys.path.pop(0)

if __name__ == '__main__':
    options, args = parser.parse_args()
    _loadaddon()
    if options.list_features:
        list_features()
        sys.exit(0)

    if options.test_features:
        sys.exit(test_features())

    hghave.require(args)