tests/test-ui-color.py

exthelper: improve docs to indicate what module vars are needed

I recently tried creating an extension "from scratch" using exthelper, and it
wasn't obvious that you needed these. I believe that a careful reading of one of
the comments would tell you that they were required, but it's easy to miss and
having the examples be "complete" is helpful.

Differential Revision: https://phab.mercurial-scm.org/D10295

from __future__ import absolute_import, print_function

import os
from mercurial import (
    dispatch,
    ui as uimod,
)
from mercurial.utils import stringutil

# ensure errors aren't buffered
testui = uimod.ui()
testui.pushbuffer()
testui.writenoi18n(b'buffered\n')
testui.warnnoi18n(b'warning\n')
testui.write_err(b'error\n')
print(stringutil.pprint(testui.popbuffer(), bprefix=True).decode('ascii'))

# test dispatch.dispatch with the same ui object
hgrc = open(os.environ["HGRCPATH"], 'wb')
hgrc.write(b'[extensions]\n')
hgrc.write(b'color=\n')
hgrc.close()

ui_ = uimod.ui.load()
ui_.setconfig(b'ui', b'formatted', b'True')

# we're not interested in the output, so write that to devnull
ui_.fout = open(os.devnull, 'wb')

# call some arbitrary command just so we go through
# color's wrapped _runcommand twice.
def runcmd():
    dispatch.dispatch(dispatch.request([b'version', b'-q'], ui_))


runcmd()
print("colored? %s" % (ui_._colormode is not None))
runcmd()
print("colored? %s" % (ui_._colormode is not None))