tests/test-bdiff.py
author Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
Mon, 17 Jan 2022 21:00:33 -0500
changeset 48598 011f5218ff2d
parent 43076 2372284d9457
child 48966 6000f5b25c9b
permissions -rw-r--r--
blackbox: add milliseconds to blackbox logs by default The current second granularity is often not specific enough to determine whether an hg command is happening before or after some other event. Given that starting a process takes on the order of 1ms (well, for native processes. It's quite a bit more for python processes), microseconds seems like unnecessary noise. This also lines up behavior with the rust version, where we already switched to millisecond precision. Differential Revision: https://phab.mercurial-scm.org/D12005

from __future__ import absolute_import, print_function
import collections
import struct
import unittest

from mercurial import mdiff


class diffreplace(collections.namedtuple('diffreplace', 'start end from_ to')):
    def __repr__(self):
        return 'diffreplace(%r, %r, %r, %r)' % self


class BdiffTests(unittest.TestCase):
    def assert_bdiff_applies(self, a, b):
        d = mdiff.textdiff(a, b)
        c = a
        if d:
            c = mdiff.patches(a, [d])
        self.assertEqual(
            c,
            b,
            (
                "bad diff+patch result from\n  %r to\n  "
                "%r: \nbdiff: %r\npatched: %r" % (a, b, d, c[:200])
            ),
        )

    def assert_bdiff(self, a, b):
        self.assert_bdiff_applies(a, b)
        self.assert_bdiff_applies(b, a)

    def test_bdiff_basic(self):
        cases = [
            (b"a\nc\n\n\n\n", b"a\nb\n\n\n"),
            (b"a\nb\nc\n", b"a\nc\n"),
            (b"", b""),
            (b"a\nb\nc", b"a\nb\nc"),
            (b"a\nb\nc\nd\n", b"a\nd\n"),
            (b"a\nb\nc\nd\n", b"a\nc\ne\n"),
            (b"a\nb\nc\n", b"a\nc\n"),
            (b"a\n", b"c\na\nb\n"),
            (b"a\n", b""),
            (b"a\n", b"b\nc\n"),
            (b"a\n", b"c\na\n"),
            (b"", b"adjfkjdjksdhfksj"),
            (b"", b"ab"),
            (b"", b"abc"),
            (b"a", b"a"),
            (b"ab", b"ab"),
            (b"abc", b"abc"),
            (b"a\n", b"a\n"),
            (b"a\nb", b"a\nb"),
        ]
        for a, b in cases:
            self.assert_bdiff(a, b)

    def showdiff(self, a, b):
        bin = mdiff.textdiff(a, b)
        pos = 0
        q = 0
        actions = []
        while pos < len(bin):
            p1, p2, l = struct.unpack(">lll", bin[pos : pos + 12])
            pos += 12
            if p1:
                actions.append(a[q:p1])
            actions.append(diffreplace(p1, p2, a[p1:p2], bin[pos : pos + l]))
            pos += l
            q = p2
        if q < len(a):
            actions.append(a[q:])
        return actions

    def test_issue1295(self):
        cases = [
            (
                b"x\n\nx\n\nx\n\nx\n\nz\n",
                b"x\n\nx\n\ny\n\nx\n\nx\n\nz\n",
                [
                    b'x\n\nx\n\n',
                    diffreplace(6, 6, b'', b'y\n\n'),
                    b'x\n\nx\n\nz\n',
                ],
            ),
            (
                b"x\n\nx\n\nx\n\nx\n\nz\n",
                b"x\n\nx\n\ny\n\nx\n\ny\n\nx\n\nz\n",
                [
                    b'x\n\nx\n\n',
                    diffreplace(6, 6, b'', b'y\n\n'),
                    b'x\n\n',
                    diffreplace(9, 9, b'', b'y\n\n'),
                    b'x\n\nz\n',
                ],
            ),
        ]
        for old, new, want in cases:
            self.assertEqual(self.showdiff(old, new), want)

    def test_issue1295_varies_on_pure(self):
        # we should pick up abbbc. rather than bc.de as the longest match
        got = self.showdiff(
            b"a\nb\nb\nb\nc\n.\nd\ne\n.\nf\n",
            b"a\nb\nb\na\nb\nb\nb\nc\n.\nb\nc\n.\nd\ne\nf\n",
        )
        want_c = [
            b'a\nb\nb\n',
            diffreplace(6, 6, b'', b'a\nb\nb\nb\nc\n.\n'),
            b'b\nc\n.\nd\ne\n',
            diffreplace(16, 18, b'.\n', b''),
            b'f\n',
        ]
        want_pure = [
            diffreplace(0, 0, b'', b'a\nb\nb\n'),
            b'a\nb\nb\nb\nc\n.\n',
            diffreplace(12, 12, b'', b'b\nc\n.\n'),
            b'd\ne\n',
            diffreplace(16, 18, b'.\n', b''),
            b'f\n',
        ]
        self.assertTrue(
            got in (want_c, want_pure),
            'got: %r, wanted either %r or %r' % (got, want_c, want_pure),
        )

    def test_fixws(self):
        cases = [
            (b" \ta\r b\t\n", b"ab\n", 1),
            (b" \ta\r b\t\n", b" a b\n", 0),
            (b"", b"", 1),
            (b"", b"", 0),
        ]
        for a, b, allws in cases:
            c = mdiff.fixws(a, allws)
            self.assertEqual(
                c, b, 'fixws(%r) want %r got %r (allws=%r)' % (a, b, c, allws)
            )

    def test_nice_diff_for_trivial_change(self):
        self.assertEqual(
            self.showdiff(
                b''.join(b'<%d\n-\n' % i for i in range(5)),
                b''.join(b'>%d\n-\n' % i for i in range(5)),
            ),
            [
                diffreplace(0, 3, b'<0\n', b'>0\n'),
                b'-\n',
                diffreplace(5, 8, b'<1\n', b'>1\n'),
                b'-\n',
                diffreplace(10, 13, b'<2\n', b'>2\n'),
                b'-\n',
                diffreplace(15, 18, b'<3\n', b'>3\n'),
                b'-\n',
                diffreplace(20, 23, b'<4\n', b'>4\n'),
                b'-\n',
            ],
        )

    def test_prefer_appending(self):
        # 1 line to 3 lines
        self.assertEqual(
            self.showdiff(b'a\n', b'a\n' * 3),
            [b'a\n', diffreplace(2, 2, b'', b'a\na\n')],
        )
        # 1 line to 5 lines
        self.assertEqual(
            self.showdiff(b'a\n', b'a\n' * 5),
            [b'a\n', diffreplace(2, 2, b'', b'a\na\na\na\n')],
        )

    def test_prefer_removing_trailing(self):
        # 3 lines to 1 line
        self.assertEqual(
            self.showdiff(b'a\n' * 3, b'a\n'),
            [b'a\n', diffreplace(2, 6, b'a\na\n', b'')],
        )
        # 5 lines to 1 line
        self.assertEqual(
            self.showdiff(b'a\n' * 5, b'a\n'),
            [b'a\n', diffreplace(2, 10, b'a\na\na\na\n', b'')],
        )


if __name__ == '__main__':
    import silenttestrunner

    silenttestrunner.main(__name__)