tests/test-mdiff.py

debugcommands: introduce actions to perform deterministic reads

"readavailable" is useful as a debugging device to see what data is
available on a pipe. But the mechanism isn't deterministic because
what's available on a pipe is highly conditional on timing, system
load, OS behavior, etc. This makes it not suitable for tests.

We introduce "ereadline," "read," and "eread" for performing
deterministic I/O operations (at least on blocking file descriptors).

We stop short of converting existing consumers of "readavailable"
in tests because we're working out race conditions and deadlocks
on Windows. But the goal is to eventually move tests away from
"readavailable" to these new APIs.

Differential Revision: https://phab.mercurial-scm.org/D2720

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__)