tests/testlib/ext-sidedata-5.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.

# coding: utf8
# ext-sidedata-5.py - small extension to test (differently still) the sidedata
# logic
#
# Simulates a server for a simple sidedata exchange.
#
# Copyright 2021 Raphaël Gomès <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.


import hashlib
import struct

from mercurial import (
    extensions,
    revlog,
)


from mercurial.revlogutils import sidedata as sidedatamod
from mercurial.revlogutils import constants

NO_FLAGS = (0, 0)


def compute_sidedata_1(repo, revlog, rev, sidedata, text=None):
    sidedata = sidedata.copy()
    if text is None:
        text = revlog.revision(rev)
    sidedata[sidedatamod.SD_TEST1] = struct.pack('>I', len(text))
    return sidedata, NO_FLAGS


def compute_sidedata_2(repo, revlog, rev, sidedata, text=None):
    sidedata = sidedata.copy()
    if text is None:
        text = revlog.revision(rev)
    sha256 = hashlib.sha256(text).digest()
    sidedata[sidedatamod.SD_TEST2] = struct.pack('>32s', sha256)
    return sidedata, NO_FLAGS


def reposetup(ui, repo):
    # Sidedata keys happen to be the same as the categories, easier for testing.
    for kind in constants.ALL_KINDS:
        repo.register_sidedata_computer(
            kind,
            sidedatamod.SD_TEST1,
            (sidedatamod.SD_TEST1,),
            compute_sidedata_1,
            0,
        )
        repo.register_sidedata_computer(
            kind,
            sidedatamod.SD_TEST2,
            (sidedatamod.SD_TEST2,),
            compute_sidedata_2,
            0,
        )

    # We don't register sidedata computers because we don't care within these
    # tests
    repo.register_wanted_sidedata(sidedatamod.SD_TEST1)
    repo.register_wanted_sidedata(sidedatamod.SD_TEST2)


def wrapaddrevision(
    orig, self, text, transaction, link, p1, p2, *args, **kwargs
):
    if kwargs.get('sidedata') is None:
        kwargs['sidedata'] = {}
    sd = kwargs['sidedata']
    ## let's store some arbitrary data just for testing
    # text length
    sd[sidedatamod.SD_TEST1] = struct.pack('>I', len(text))
    # and sha2 hashes
    sha256 = hashlib.sha256(text).digest()
    sd[sidedatamod.SD_TEST2] = struct.pack('>32s', sha256)
    return orig(self, text, transaction, link, p1, p2, *args, **kwargs)


def extsetup(ui):
    extensions.wrapfunction(revlog.revlog, 'addrevision', wrapaddrevision)