tests/fakedirstatewritetime.py

commit: use `dirstate.change_files` to scope the associated `addremove`

This was significantly more complicated than I expected, because multiple
extensions get in the way.

I introduced a context that lazily open the transaction and associated context
to work around these complication. See the inline documentation for details.

Introducing the wrapping transaction remove the need for dirstate-guard (one of
the ultimate goal of all this), and slightly affect the result of a `hg
rollback` after a `hg commit --addremove`. That last part is deemed fine. It
aligns the behavior with what happens after a failed `hg commit --addremove` and
nobody should be using `hg rollback` anyway.

The small output change in the test come from the different transaction timing
and fact the transaction now backup the dirstate before the addremove, which
might mean "no file to backup" when the repository starts from an empty state.

# extension to emulate invoking 'dirstate.write()' at the time
# specified by '[fakedirstatewritetime] fakenow', only when
# 'dirstate.write()' is invoked via functions below:
#
#   - 'workingctx._poststatusfixup()' (= 'repo.status()')
#   - 'committablectx.markcommitted()'


from mercurial import (
    context,
    dirstatemap as dirstatemapmod,
    extensions,
    policy,
    registrar,
)
from mercurial.dirstateutils import timestamp
from mercurial.utils import dateutil

try:
    from mercurial import rustext

    rustext.__name__  # force actual import (see hgdemandimport)
except ImportError:
    rustext = None

configtable = {}
configitem = registrar.configitem(configtable)

configitem(
    b'fakedirstatewritetime',
    b'fakenow',
    default=None,
)

parsers = policy.importmod('parsers')
has_rust_dirstate = policy.importrust('dirstate') is not None


def pack_dirstate(orig, dmap, copymap, pl):
    return orig(dmap, copymap, pl)


def fakewrite(ui, func):
    # fake "now" of 'pack_dirstate' only if it is invoked while 'func'

    fakenow = ui.config(b'fakedirstatewritetime', b'fakenow')
    if not fakenow:
        # Execute original one, if fakenow isn't configured. This is
        # useful to prevent subrepos from executing replaced one,
        # because replacing 'parsers.pack_dirstate' is also effective
        # in subrepos.
        return func()

    # parsing 'fakenow' in YYYYmmddHHMM format makes comparison between
    # 'fakenow' value and 'touch -t YYYYmmddHHMM' argument easy
    fakenow = dateutil.parsedate(fakenow, [b'%Y%m%d%H%M'])[0]
    fakenow = timestamp.timestamp((fakenow, 0, False))

    if has_rust_dirstate:
        # The Rust implementation does not use public parse/pack dirstate
        # to prevent conversion round-trips
        orig_dirstatemap_write = dirstatemapmod.dirstatemap.write
        wrapper = lambda self, tr, st: orig_dirstatemap_write(self, tr, st)
        dirstatemapmod.dirstatemap.write = wrapper

    orig_get_fs_now = timestamp.get_fs_now
    wrapper = lambda *args: pack_dirstate(orig_pack_dirstate, *args)

    orig_module = parsers
    orig_pack_dirstate = parsers.pack_dirstate

    orig_module.pack_dirstate = wrapper
    timestamp.get_fs_now = (
        lambda *args: fakenow
    )  # XXX useless for this purpose now
    try:
        return func()
    finally:
        orig_module.pack_dirstate = orig_pack_dirstate
        timestamp.get_fs_now = orig_get_fs_now
        if has_rust_dirstate:
            dirstatemapmod.dirstatemap.write = orig_dirstatemap_write


def _poststatusfixup(orig, workingctx, status, fixup):
    ui = workingctx.repo().ui
    return fakewrite(ui, lambda: orig(workingctx, status, fixup))


def markcommitted(orig, committablectx, node):
    ui = committablectx.repo().ui
    return fakewrite(ui, lambda: orig(committablectx, node))


def extsetup(ui):
    extensions.wrapfunction(
        context.workingctx, '_poststatusfixup', _poststatusfixup
    )
    extensions.wrapfunction(context.workingctx, 'markcommitted', markcommitted)