tests/fakemergerecord.py

tests: add tests for when stdout or stderr is connected to `os.devnull`

The original motivation was that creating PTYs on Windows is not possible, but
`NUL` is recognized as a TTY, so we can have at least some test coverage for
the TTY case. I think it doesn’t hurt to run the test cases on all systems.

# Extension to write out fake unsupported records into the merge state
#
#

from __future__ import absolute_import

from mercurial import (
    mergestate as mergestatemod,
    registrar,
)

cmdtable = {}
command = registrar.command(cmdtable)


@command(
    b'fakemergerecord',
    [
        (b'X', b'mandatory', None, b'add a fake mandatory record'),
        (b'x', b'advisory', None, b'add a fake advisory record'),
    ],
    '',
)
def fakemergerecord(ui, repo, *pats, **opts):
    with repo.wlock():
        ms = mergestatemod.mergestate.read(repo)
        records = ms._makerecords()
        if opts.get('mandatory'):
            records.append((b'X', b'mandatory record'))
        if opts.get('advisory'):
            records.append((b'x', b'advisory record'))
        ms._writerecords(records)