tests/test-config-env.py

revert: do not reverse hunks in interactive when REV is not parent (issue5096)

And introduce a new "apply" operation verb for this case as suggested in
issue5096. This replaces the no longer used "revert" operation.

In interactive revert, when reverting to something else that the parent
revision, display an "apply this change" message with a diff that is not
reversed.

The rationale is that `hg revert -i -r REV` will show hunks of the diff from
the working directory to REV and prompt the user to select them for applying
(to working directory). This contradicts dcc56e10c23b in which it was
decided to have the "direction" of prompted hunks reversed. Later on
[1], there was a broad consensus (but no decision) towards the "as to
be applied direction". Now that --interactive is no longer experimental
(5910db5d1913), it's time to switch and thus we drop no longer used
"experimental.revertalternateinteractivemode" configuration option.

[1]: https://www.mercurial-scm.org/pipermail/mercurial-devel/2016-November/090142.html


.. feature::

  When interactive revert is run against a revision other than the working
  directory parent, the diff shown is the diff to *apply* to the working directory,
  rather than the diff to *discard* from the working copy. This is in line with
  related user experiences with `git` and appears to be less confusing with
  `ui.interface=curses`.

# Test the config layer generated by environment variables

from __future__ import absolute_import, print_function

import os

from mercurial import (
    encoding,
    rcutil,
    ui as uimod,
    util,
)

testtmp = encoding.environ['TESTTMP']

# prepare hgrc files
def join(name):
    return os.path.join(testtmp, name)

with open(join('sysrc'), 'w') as f:
    f.write('[ui]\neditor=e0\n[pager]\npager=p0\n')

with open(join('userrc'), 'w') as f:
    f.write('[ui]\neditor=e1')

# replace rcpath functions so they point to the files above
def systemrcpath():
    return [join('sysrc')]

def userrcpath():
    return [join('userrc')]

rcutil.systemrcpath = systemrcpath
rcutil.userrcpath = userrcpath
os.path.isdir = lambda x: False # hack: do not load default.d/*.rc

# utility to print configs
def printconfigs(env):
    encoding.environ = env
    rcutil._rccomponents = None # reset cache
    ui = uimod.ui.load()
    for section, name, value in ui.walkconfig():
        source = ui.configsource(section, name)
        print('%s.%s=%s # %s' % (section, name, value, util.pconvert(source)))
    print('')

# environment variable overrides
printconfigs({})
printconfigs({'EDITOR': 'e2', 'PAGER': 'p2'})