tests/test-bdiff.py

pycompat: add bytestr wrapper which mostly acts as a Python 2 str

This allows us to handle bytes in mostly the same manner as Python 2 str,
so we can get rid of ugly s[i:i + 1] hacks:

  s = bytestr(s)
  while i < len(s):
      c = s[i]
      ...

This is the simpler version of the previous RFC patch which tried to preserve
the bytestr type if possible. New version simply drops the bytestr wrapping
so we aren't likely to pass a bytestr to a function that expects Python 3
bytes.

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

from mercurial import (
    bdiff,
    mpatch,
)

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

    def showdiff(self, a, b):
        bin = bdiff.bdiff(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 = [
            ("x\n\nx\n\nx\n\nx\n\nz\n", "x\n\nx\n\ny\n\nx\n\nx\n\nz\n",
             ['x\n\nx\n\n', diffreplace(6, 6, '', 'y\n\n'), 'x\n\nx\n\nz\n']),
            ("x\n\nx\n\nx\n\nx\n\nz\n", "x\n\nx\n\ny\n\nx\n\ny\n\nx\n\nz\n",
             ['x\n\nx\n\n',
              diffreplace(6, 6, '', 'y\n\n'),
              'x\n\n',
              diffreplace(9, 9, '', 'y\n\n'),
              '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("a\nb\nb\nb\nc\n.\nd\ne\n.\nf\n",
                            "a\nb\nb\na\nb\nb\nb\nc\n.\nb\nc\n.\nd\ne\nf\n")
        want_c = ['a\nb\nb\n',
                  diffreplace(6, 6, '', 'a\nb\nb\nb\nc\n.\n'),
                  'b\nc\n.\nd\ne\n',
                  diffreplace(16, 18, '.\n', ''),
                  'f\n']
        want_pure = [diffreplace(0, 0, '', 'a\nb\nb\n'),
                     'a\nb\nb\nb\nc\n.\n',
                     diffreplace(12, 12, '', 'b\nc\n.\n'),
                     'd\ne\n',
                     diffreplace(16, 18, '.\n', ''), 'f\n']
        self.assert_(got in (want_c, want_pure),
                     'got: %r, wanted either %r or %r' % (
                         got, want_c, want_pure))

    def test_fixws(self):
        cases = [
            (" \ta\r b\t\n", "ab\n", 1),
            (" \ta\r b\t\n", " a b\n", 0),
            ("", "", 1),
            ("", "", 0),
        ]
        for a, b, allws in cases:
            c = bdiff.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(
            ''.join('<%s\n-\n' % i for i in range(5)),
            ''.join('>%s\n-\n' % i for i in range(5))),
                         [diffreplace(0, 3, '<0\n', '>0\n'),
                          '-\n',
                          diffreplace(5, 8, '<1\n', '>1\n'),
                          '-\n',
                          diffreplace(10, 13, '<2\n', '>2\n'),
                          '-\n',
                          diffreplace(15, 18, '<3\n', '>3\n'),
                          '-\n',
                          diffreplace(20, 23, '<4\n', '>4\n'),
                          '-\n'])

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

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

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