tests/test-ctxmanager.py

tests: escape bytes setting MSB in input of grep for portability

GNU grep (2.21-2 or later) assumes that input is encoded in LC_CTYPE,
and input is binary if it contains byte sequence not valid for that
encoding.

For example, if locale is configured as C, a byte setting most
significant bit (MSB) makes such GNU grep show "Binary file <FILENAME>
matches" message instead of matched lines unintentionally.

This behavior is recognized as a bug, and fixed in GNU grep 2.25-1 or
later. But some distributions are shipped with such buggy version
(e.g. Ubuntu xenial, which is used by launchpad buildbot).

    http://debbugs.gnu.org/cgi/bugreport.cgi?bug=19230
    https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=800670
    http://packages.ubuntu.com/xenial/grep

This causes failure of test-commit-interactive.t, which applies grep
on CP932 byte sequence since 1111e84de635.

But, explicit setting LC_CTYPE for CP932 might cause another problem,
because it can't be assumed that all environment running Mercurial
tests allows arbitrary locale setting.

To resolve this issue, this patch escapes bytes setting MSB in input
of grep.

For this purpose:

  - str.encode('string-escape') isn't useful, because it escapes also
    control code (less than 0x20), and makes EOL handling complicated

  - "f --hexdump" isn't useful, because it isn't line-oriented

  - "sed -n" seems reasonable, but "sed" itself sometimes causes
    portability issue, too (e.g. 900767dfa80d or afb86ee925bf)

This patch is posted with "stable" flag, because 1111e84de635 is on
stable branch.

from __future__ import absolute_import

import silenttestrunner
import unittest

from mercurial import util

class contextmanager(object):
    def __init__(self, name, trace):
        self.name = name
        self.entered = False
        self.exited = False
        self.trace = trace

    def __enter__(self):
        self.entered = True
        self.trace(('enter', self.name))
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.exited = exc_type, exc_val, exc_tb
        self.trace(('exit', self.name))

    def __repr__(self):
        return '<ctx %r>' % self.name

class ctxerror(Exception):
    pass

class raise_on_enter(contextmanager):
    def __enter__(self):
        self.trace(('raise', self.name))
        raise ctxerror(self.name)

class raise_on_exit(contextmanager):
    def __exit__(self, exc_type, exc_val, exc_tb):
        self.trace(('raise', self.name))
        raise ctxerror(self.name)

def ctxmgr(name, trace):
    return lambda: contextmanager(name, trace)

class test_ctxmanager(unittest.TestCase):
    def test_basics(self):
        trace = []
        addtrace = trace.append
        with util.ctxmanager(ctxmgr('a', addtrace), ctxmgr('b', addtrace)) as c:
            a, b = c.enter()
            c.atexit(addtrace, ('atexit', 'x'))
            c.atexit(addtrace, ('atexit', 'y'))
        self.assertEqual(trace, [('enter', 'a'), ('enter', 'b'),
                                 ('atexit', 'y'), ('atexit', 'x'),
                                 ('exit', 'b'), ('exit', 'a')])

    def test_raise_on_enter(self):
        trace = []
        addtrace = trace.append
        def go():
            with util.ctxmanager(ctxmgr('a', addtrace),
                                 lambda: raise_on_enter('b', addtrace)) as c:
                c.enter()
                addtrace('unreachable')
        self.assertRaises(ctxerror, go)
        self.assertEqual(trace, [('enter', 'a'), ('raise', 'b'), ('exit', 'a')])

    def test_raise_on_exit(self):
        trace = []
        addtrace = trace.append
        def go():
            with util.ctxmanager(ctxmgr('a', addtrace),
                                 lambda: raise_on_exit('b', addtrace)) as c:
                c.enter()
                addtrace('running')
        self.assertRaises(ctxerror, go)
        self.assertEqual(trace, [('enter', 'a'), ('enter', 'b'), 'running',
                                 ('raise', 'b'), ('exit', 'a')])

if __name__ == '__main__':
    silenttestrunner.main(__name__)