view tests/test-mdiff.py @ 37212:f09a2eab11cf

server: add an error feedback mechanism for when the daemon fails to launch

There's a recurring problem on Windows where `hg serve -d` will randomly fail to
spawn a detached process.  The reason for the failure is completely hidden, and
it takes hours to get a single failure on my laptop.  All this does is redirect
stdout/stderr of the child to a file until the lock file is freed, and then the
parent dumps it out if it fails to spawn.

I chose to put the output into the lock file because that is always cleaned up.
There's no way to report errors after that anyway.  On Windows, killdaemons.py
is roughly `kill -9`, so this ensures that junk won't pile up.

This may end up being a case of EADDRINUSE.  At least that's what I saw spit out
a few times (among other odd errors and missing output on Windows).  But I also
managed to get the same thing on Fedora 26 by running test-hgwebdir.t with
--loop -j10 for several hours.  Running `netstat` immediately after killing that
run printed a wall of sockets in the TIME_WAIT state, which were gone a couple
seconds later.  I couldn't match up ports that failed, because --loop doesn't
print out the message about the port that was used.  So maybe the fix is to
rotate the use of HGPORT[12] in the tests.  But, let's collect some more data
first.

from __future__ import absolute_import
from __future__ import print_function

import unittest

from mercurial import (
    mdiff,
)

class splitnewlinesTests(unittest.TestCase):

    def test_splitnewlines(self):
        cases = {b'a\nb\nc\n': [b'a\n', b'b\n', b'c\n'],
                 b'a\nb\nc': [b'a\n', b'b\n', b'c'],
                 b'a\nb\nc\n\n': [b'a\n', b'b\n', b'c\n', b'\n'],
                 b'': [],
                 b'abcabc': [b'abcabc'],
                 }
        for inp, want in cases.items():
            self.assertEqual(mdiff.splitnewlines(inp), want)

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