hgext/bookflow.py

tests: show the files fields of changelogs for many merges

I don't think there's coverage for many of the subtle cases, and I
found it hard to understand what the code is doing by reading it.  The
test takes 40s to run on a laptop, or 9s with --chg.

I have yet to find a description of what the files field is supposed
to be for merges. I thought it could be one of:
1. the files added/modified/removed relative to p1 (wouldn't seem
  useful, but `hg diff -c -r mergerev` has this behavior)
2. the files with filelog nodes not in either parent (i.e., what is
needed to create a bundle out of a commit)
3. the files added/removed/modified files by merge itself [1]

It's clearly not 1, because file contents merges are symmetric. It's
clearly not 2 because removed files and exec bit changes are
listed. It's also not 3 but I think it's intended to be 3 and the
differences are bugs.

Assuming 3, the test shows that, for merges, the list of files both
overapproximates and underapproximates. All the cases involve file
changes not in the filelog but in the manifest (existence of file
at revision, exec bit and file vs symlink).

I didn't look at all underapproximations, but they looked minor. The
two overapproximations are problematic though because they both cause
potentially long lists of files when merging cleanly.


[1] even what it means for the merge commit itself to change a file is
not completely trivial. A file in the merge being the same as in one
of the parent is too lax as it would consider that merges change
nothing when they revert all the changes done on one side. The
criteria used in the test and in the next commit for "merge didn't
touch a file" is:
- the parents and the merge all have the same file
- or, one parent didn't touch the file and the other parent contains
  the same file as the merge

Differential Revision: https://phab.mercurial-scm.org/D6612

"""implements bookmark-based branching (EXPERIMENTAL)

 - Disables creation of new branches (config: enable_branches=False).
 - Requires an active bookmark on commit (config: require_bookmark=True).
 - Doesn't move the active bookmark on update, only on commit.
 - Requires '--rev' for moving an existing bookmark.
 - Protects special bookmarks (config: protect=@).

 flow related commands

    :hg book NAME: create a new bookmark
    :hg book NAME -r REV: move bookmark to revision (fast-forward)
    :hg up|co NAME: switch to bookmark
    :hg push -B .: push active bookmark
"""
from __future__ import absolute_import

from mercurial.i18n import _
from mercurial import (
    bookmarks,
    commands,
    error,
    extensions,
    registrar,
)

MY_NAME = 'bookflow'

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

configitem(MY_NAME, 'protect', ['@'])
configitem(MY_NAME, 'require-bookmark', True)
configitem(MY_NAME, 'enable-branches', False)

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

def commit_hook(ui, repo, **kwargs):
    active = repo._bookmarks.active
    if active:
        if active in ui.configlist(MY_NAME, 'protect'):
            raise error.Abort(
                _('cannot commit, bookmark %s is protected') % active)
        if not cwd_at_bookmark(repo, active):
            raise error.Abort(
       _('cannot commit, working directory out of sync with active bookmark'),
                hint=_("run 'hg up %s'") % active)
    elif ui.configbool(MY_NAME, 'require-bookmark', True):
        raise error.Abort(_('cannot commit without an active bookmark'))
    return 0

def bookmarks_update(orig, repo, parents, node):
    if len(parents) == 2:
        # called during commit
        return orig(repo, parents, node)
    else:
        # called during update
        return False

def bookmarks_addbookmarks(
        orig, repo, tr, names, rev=None, force=False, inactive=False):
    if not rev:
        marks = repo._bookmarks
        for name in names:
            if name in marks:
                raise error.Abort(_(
                    "bookmark %s already exists, to move use the --rev option"
                    ) % name)
    return orig(repo, tr, names, rev, force, inactive)

def commands_commit(orig, ui, repo, *args, **opts):
    commit_hook(ui, repo)
    return orig(ui, repo, *args, **opts)

def commands_pull(orig, ui, repo, *args, **opts):
    rc = orig(ui, repo, *args, **opts)
    active = repo._bookmarks.active
    if active and not cwd_at_bookmark(repo, active):
        ui.warn(_(
            "working directory out of sync with active bookmark, run "
            "'hg up %s'"
        ) % active)
    return rc

def commands_branch(orig, ui, repo, label=None, **opts):
    if label and not opts.get(r'clean') and not opts.get(r'rev'):
        raise error.Abort(
         _("creating named branches is disabled and you should use bookmarks"),
            hint="see 'hg help bookflow'")
    return orig(ui, repo, label, **opts)

def cwd_at_bookmark(repo, mark):
    mark_id = repo._bookmarks[mark]
    cur_id = repo.lookup('.')
    return cur_id == mark_id

def uisetup(ui):
    extensions.wrapfunction(bookmarks, 'update', bookmarks_update)
    extensions.wrapfunction(bookmarks, 'addbookmarks', bookmarks_addbookmarks)
    extensions.wrapcommand(commands.table, 'commit', commands_commit)
    extensions.wrapcommand(commands.table, 'pull', commands_pull)
    if not ui.configbool(MY_NAME, 'enable-branches'):
        extensions.wrapcommand(commands.table, 'branch', commands_branch)