mercurial/txnutil.py

tests: add test for remotefilelog interactions with hgweb

It's not uncommon for hg users to rely on hgweb as a simple GUI and
history browser (I do this all the time on Mercurial), but we lack any
tests to ensure things keep working.

At present, this merely demonstrates the "view contents of a single
file" endpoint is broken. I'll fix that in a subsequent change.

Differential Revision: https://phab.mercurial-scm.org/D8298

# txnutil.py - transaction related utilities
#
#  Copyright FUJIWARA Katsunori <[e-mail]> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import errno

from . import encoding


def mayhavepending(root):
    '''return whether 'root' may have pending changes, which are
    visible to this process.
    '''
    return root == encoding.environ.get(b'HG_PENDING')


def trypending(root, vfs, filename, **kwargs):
    '''Open  file to be read according to HG_PENDING environment variable

    This opens '.pending' of specified 'filename' only when HG_PENDING
    is equal to 'root'.

    This returns '(fp, is_pending_opened)' tuple.
    '''
    if mayhavepending(root):
        try:
            return (vfs(b'%s.pending' % filename, **kwargs), True)
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
    return (vfs(filename, **kwargs), False)