view tests/test-bdiff.py @ 42175:cd1bede340b0 stable

setup: tweak error message for Python 3

We now have beta support for Python 3. In my opinion, it isn't
yet stable enough to allow `pip install Mercurial` to work with
Python 3 out of the box: we don't want people accidentally using
Mercurial with Python 3 just yet.

But I do think we should be more friendly about informing people
of their options.

This commit tweaks the error message that users see when running
setup.py with Python 3. We instruct them about the current level
of Python 3 support, point them at the wiki for more info, and
give them instructions on how to bypass the check.

As part of this, I also changed which version value is printed,
as we were printing a named tuple before.

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__)