tests/test-config-env.py

rust-dirstate: call rust dirstatemap from Python

Since Rust-backed Python classes cannot be used as baseclasses (for
rust-cpython anyway), we use composition rather than inheritance.

This also allows us to keep the IO operations in the Python side, removing
(for now) the need to rewrite VFS in Rust, which would be a heavy undertaking.

Differential Revision: https://phab.mercurial-scm.org/D6634

# 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,
)

from mercurial.utils import (
    procutil,
)

testtmp = encoding.environ[b'TESTTMP']

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

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

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

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

def userrcpath():
    return [join(b'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)
        procutil.stdout.write(b'%s.%s=%s # %s\n'
                              % (section, name, value, util.pconvert(source)))
    procutil.stdout.write(b'\n')

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