view tests/test-simplemerge.py @ 48507:58a3be48ddd2

simplemerge: stop merging file flags

As 384df4db6520 (merge: merge file flags together with file content,
2013-01-09) explains, we shouldn't do a 3-way merge of the
symlink. However, since 84614212ae39 (flags: actually merge flags in
simplemerge, 2020-05-16), we do that in
`simplemerge.simplemerge()`. What's more, the merging of the
executable flag there isn't actually necessary; it was made a no-op by
the very next commit, i.e. 4234c9af515d (flags: read flag from
dirstate/disk for workingcopyctx (issue5743), 2020-05-16).

I found the overall flag-merging code (not the bit in
`simplemerge.py`) very hard to follow, but I think I now finally
understand how it works. `mergestate.resolve()` calculates the merged
file flags and sets them on the local side of the merge (confusingly
by calling `_restore_backup()`). Then it calls
`filemerge.filemerge()`, which in turn calls
`simplemerge.simplemerge()` (if premerge is enabled). That means that
the flags on the local side `fcs.flags()` are already correct when the
flag-merging code in `simplemerge.simplemerge()` runs. Interestingly,
that code still works when the local side already has the merged
value, it just doesn't change the value. Here's a truth table to
explain why:

```
BLOMCAR
0000000
0011111
0101011
0111111
1000000
1010000
1100000
1111101
```

B: Base
L: Local
O: Other
M: Merged flags from `mergestate.resolve()`, i.e. what's called "local"
   when we get to `simplemerge.simplemerge()`
C: `commonflags` in `simplemerge.simplemerge()`, i.e. `M & O`
A: `addedflags` in `simplemerge.simplemerge()`, i.e. `(M ^ O) - B`
R: Re-merged flags `simplemerge.simplemerge()`, i.e. `C | A`

As you can see, the re-merged flags are always unchanged compared to
the initial merged flags (R equals M).

Therefore, this patch effectively backs out 84614212ae39. (I might
later refactor this code to have the flags explicitly passed in.)

`simplemerge.simplemerge()` is also called from
`contrib/simplemerge.py`, but that code never passes any flags.

Differential Revision: https://phab.mercurial-scm.org/D11879

# Copyright (C) 2004, 2005 Canonical Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, see <http://www.gnu.org/licenses/>.

from __future__ import absolute_import

import unittest
from mercurial import (
    error,
    simplemerge,
    util,
)

from mercurial.utils import stringutil

TestCase = unittest.TestCase
# bzr compatible interface, for the tests
class Merge3(simplemerge.Merge3Text):
    """3-way merge of texts.

    Given BASE, OTHER, THIS, tries to produce a combined text
    incorporating the changes from both BASE->OTHER and BASE->THIS.
    All three will typically be sequences of lines."""

    def __init__(self, base, a, b):
        basetext = b'\n'.join([i.strip(b'\n') for i in base] + [b''])
        atext = b'\n'.join([i.strip(b'\n') for i in a] + [b''])
        btext = b'\n'.join([i.strip(b'\n') for i in b] + [b''])
        if (
            stringutil.binary(basetext)
            or stringutil.binary(atext)
            or stringutil.binary(btext)
        ):
            raise error.Abort(b"don't know how to merge binary files")
        simplemerge.Merge3Text.__init__(
            self, basetext, atext, btext, base, a, b
        )


CantReprocessAndShowBase = simplemerge.CantReprocessAndShowBase


def split_lines(t):
    return util.stringio(t).readlines()


############################################################
# test case data from the gnu diffutils manual
# common base
TZU = split_lines(
    b"""     The Nameless is the origin of Heaven and Earth;
     The named is the mother of all things.

     Therefore let there always be non-being,
       so we may see their subtlety,
     And let there always be being,
       so we may see their outcome.
     The two are the same,
     But after they are produced,
       they have different names.
     They both may be called deep and profound.
     Deeper and more profound,
     The door of all subtleties!
"""
)

LAO = split_lines(
    b"""     The Way that can be told of is not the eternal Way;
     The name that can be named is not the eternal name.
     The Nameless is the origin of Heaven and Earth;
     The Named is the mother of all things.
     Therefore let there always be non-being,
       so we may see their subtlety,
     And let there always be being,
       so we may see their outcome.
     The two are the same,
     But after they are produced,
       they have different names.
"""
)


TAO = split_lines(
    b"""     The Way that can be told of is not the eternal Way;
     The name that can be named is not the eternal name.
     The Nameless is the origin of Heaven and Earth;
     The named is the mother of all things.

     Therefore let there always be non-being,
       so we may see their subtlety,
     And let there always be being,
       so we may see their result.
     The two are the same,
     But after they are produced,
       they have different names.

       -- The Way of Lao-Tzu, tr. Wing-tsit Chan

"""
)

MERGED_RESULT = split_lines(
    b"""\
     The Way that can be told of is not the eternal Way;
     The name that can be named is not the eternal name.
     The Nameless is the origin of Heaven and Earth;
     The Named is the mother of all things.
     Therefore let there always be non-being,
       so we may see their subtlety,
     And let there always be being,
       so we may see their result.
     The two are the same,
     But after they are produced,
       they have different names.\
\n<<<<<<< LAO\
\n=======

       -- The Way of Lao-Tzu, tr. Wing-tsit Chan
\
\n>>>>>>> TAO
"""
)


class TestMerge3(TestCase):
    def log(self, msg):
        pass

    def test_no_changes(self):
        """No conflicts because nothing changed"""
        m3 = Merge3([b'aaa', b'bbb'], [b'aaa', b'bbb'], [b'aaa', b'bbb'])

        self.assertEqual(
            list(m3.find_sync_regions()),
            [(0, 2, 0, 2, 0, 2), (2, 2, 2, 2, 2, 2)],
        )

        self.assertEqual(list(m3.merge_regions()), [(b'unchanged', 0, 2)])

        self.assertEqual(
            list(m3.merge_groups()), [(b'unchanged', [b'aaa', b'bbb'])]
        )

    def test_front_insert(self):
        m3 = Merge3([b'zz'], [b'aaa', b'bbb', b'zz'], [b'zz'])

        # todo: should use a sentinel at end as from get_matching_blocks
        # to match without zz
        self.assertEqual(
            list(m3.find_sync_regions()),
            [(0, 1, 2, 3, 0, 1), (1, 1, 3, 3, 1, 1)],
        )

        self.assertEqual(
            list(m3.merge_regions()), [(b'a', 0, 2), (b'unchanged', 0, 1)]
        )

        self.assertEqual(
            list(m3.merge_groups()),
            [(b'a', [b'aaa', b'bbb']), (b'unchanged', [b'zz'])],
        )

    def test_null_insert(self):
        m3 = Merge3([], [b'aaa', b'bbb'], [])
        # todo: should use a sentinel at end as from get_matching_blocks
        # to match without zz
        self.assertEqual(list(m3.find_sync_regions()), [(0, 0, 2, 2, 0, 0)])

        self.assertEqual(list(m3.merge_regions()), [(b'a', 0, 2)])

        self.assertEqual(list(m3.merge_lines()), [b'aaa', b'bbb'])

    def test_no_conflicts(self):
        """No conflicts because only one side changed"""
        m3 = Merge3(
            [b'aaa', b'bbb'], [b'aaa', b'111', b'bbb'], [b'aaa', b'bbb']
        )

        self.assertEqual(
            list(m3.find_sync_regions()),
            [(0, 1, 0, 1, 0, 1), (1, 2, 2, 3, 1, 2), (2, 2, 3, 3, 2, 2)],
        )

        self.assertEqual(
            list(m3.merge_regions()),
            [(b'unchanged', 0, 1), (b'a', 1, 2), (b'unchanged', 1, 2)],
        )

    def test_append_a(self):
        m3 = Merge3(
            [b'aaa\n', b'bbb\n'],
            [b'aaa\n', b'bbb\n', b'222\n'],
            [b'aaa\n', b'bbb\n'],
        )

        self.assertEqual(b''.join(m3.merge_lines()), b'aaa\nbbb\n222\n')

    def test_append_b(self):
        m3 = Merge3(
            [b'aaa\n', b'bbb\n'],
            [b'aaa\n', b'bbb\n'],
            [b'aaa\n', b'bbb\n', b'222\n'],
        )

        self.assertEqual(b''.join(m3.merge_lines()), b'aaa\nbbb\n222\n')

    def test_append_agreement(self):
        m3 = Merge3(
            [b'aaa\n', b'bbb\n'],
            [b'aaa\n', b'bbb\n', b'222\n'],
            [b'aaa\n', b'bbb\n', b'222\n'],
        )

        self.assertEqual(b''.join(m3.merge_lines()), b'aaa\nbbb\n222\n')

    def test_append_clash(self):
        m3 = Merge3(
            [b'aaa\n', b'bbb\n'],
            [b'aaa\n', b'bbb\n', b'222\n'],
            [b'aaa\n', b'bbb\n', b'333\n'],
        )

        ml = m3.merge_lines(
            name_a=b'a',
            name_b=b'b',
            start_marker=b'<<',
            mid_marker=b'--',
            end_marker=b'>>',
        )
        self.assertEqual(
            b''.join(ml),
            b'aaa\n' b'bbb\n' b'<< a\n' b'222\n' b'--\n' b'333\n' b'>> b\n',
        )

    def test_insert_agreement(self):
        m3 = Merge3(
            [b'aaa\n', b'bbb\n'],
            [b'aaa\n', b'222\n', b'bbb\n'],
            [b'aaa\n', b'222\n', b'bbb\n'],
        )

        ml = m3.merge_lines(
            name_a=b'a',
            name_b=b'b',
            start_marker=b'<<',
            mid_marker=b'--',
            end_marker=b'>>',
        )
        self.assertEqual(b''.join(ml), b'aaa\n222\nbbb\n')

    def test_insert_clash(self):
        """Both try to insert lines in the same place."""
        m3 = Merge3(
            [b'aaa\n', b'bbb\n'],
            [b'aaa\n', b'111\n', b'bbb\n'],
            [b'aaa\n', b'222\n', b'bbb\n'],
        )

        self.assertEqual(
            list(m3.find_sync_regions()),
            [(0, 1, 0, 1, 0, 1), (1, 2, 2, 3, 2, 3), (2, 2, 3, 3, 3, 3)],
        )

        self.assertEqual(
            list(m3.merge_regions()),
            [
                (b'unchanged', 0, 1),
                (b'conflict', 1, 1, 1, 2, 1, 2),
                (b'unchanged', 1, 2),
            ],
        )

        self.assertEqual(
            list(m3.merge_groups()),
            [
                (b'unchanged', [b'aaa\n']),
                (b'conflict', [], [b'111\n'], [b'222\n']),
                (b'unchanged', [b'bbb\n']),
            ],
        )

        ml = m3.merge_lines(
            name_a=b'a',
            name_b=b'b',
            start_marker=b'<<',
            mid_marker=b'--',
            end_marker=b'>>',
        )
        self.assertEqual(
            b''.join(ml),
            b'''aaa
<< a
111
--
222
>> b
bbb
''',
        )

    def test_replace_clash(self):
        """Both try to insert lines in the same place."""
        m3 = Merge3(
            [b'aaa', b'000', b'bbb'],
            [b'aaa', b'111', b'bbb'],
            [b'aaa', b'222', b'bbb'],
        )

        self.assertEqual(
            list(m3.find_sync_regions()),
            [(0, 1, 0, 1, 0, 1), (2, 3, 2, 3, 2, 3), (3, 3, 3, 3, 3, 3)],
        )

    def test_replace_multi(self):
        """Replacement with regions of different size."""
        m3 = Merge3(
            [b'aaa', b'000', b'000', b'bbb'],
            [b'aaa', b'111', b'111', b'111', b'bbb'],
            [b'aaa', b'222', b'222', b'222', b'222', b'bbb'],
        )

        self.assertEqual(
            list(m3.find_sync_regions()),
            [(0, 1, 0, 1, 0, 1), (3, 4, 4, 5, 5, 6), (4, 4, 5, 5, 6, 6)],
        )

    def test_merge_poem(self):
        """Test case from diff3 manual"""
        m3 = Merge3(TZU, LAO, TAO)
        ml = list(m3.merge_lines(b'LAO', b'TAO'))
        self.log(b'merge result:')
        self.log(b''.join(ml))
        self.assertEqual(ml, MERGED_RESULT)

    def test_binary(self):
        with self.assertRaises(error.Abort):
            Merge3([b'\x00'], [b'a'], [b'b'])

    def test_dos_text(self):
        base_text = b'a\r\n'
        this_text = b'b\r\n'
        other_text = b'c\r\n'
        m3 = Merge3(
            base_text.splitlines(True),
            other_text.splitlines(True),
            this_text.splitlines(True),
        )
        m_lines = m3.merge_lines(b'OTHER', b'THIS')
        self.assertEqual(
            b'<<<<<<< OTHER\r\nc\r\n=======\r\nb\r\n'
            b'>>>>>>> THIS\r\n'.splitlines(True),
            list(m_lines),
        )

    def test_mac_text(self):
        base_text = b'a\r'
        this_text = b'b\r'
        other_text = b'c\r'
        m3 = Merge3(
            base_text.splitlines(True),
            other_text.splitlines(True),
            this_text.splitlines(True),
        )
        m_lines = m3.merge_lines(b'OTHER', b'THIS')
        self.assertEqual(
            b'<<<<<<< OTHER\rc\r=======\rb\r'
            b'>>>>>>> THIS\r'.splitlines(True),
            list(m_lines),
        )


if __name__ == '__main__':
    import silenttestrunner

    silenttestrunner.main(__name__)