tests/test-rust-revlog.py

setup: exclude the git extension from py2 builds

This can't be built on Windows with the py2 compiler, and while old versions can
be installed via pip on Linux, I can't get the tests to run (even with py3.8)
using pygit2 0.28.2.  Some manually run commands work, and others spew stack
traces that don't occur with the current 1.4.0 release using py3.

Differential Revision: https://phab.mercurial-scm.org/D9604

from __future__ import absolute_import
import unittest

try:
    from mercurial import rustext

    rustext.__name__  # trigger immediate actual import
except ImportError:
    rustext = None
else:
    from mercurial.rustext import revlog

    # this would fail already without appropriate ancestor.__package__
    from mercurial.rustext.ancestor import LazyAncestors

from mercurial.testing import revlog as revlogtesting


@unittest.skipIf(
    rustext is None,
    "rustext module revlog relies on is not available",
)
class RustRevlogIndexTest(revlogtesting.RevlogBasedTestBase):
    def test_heads(self):
        idx = self.parseindex()
        rustidx = revlog.MixedIndex(idx)
        self.assertEqual(rustidx.headrevs(), idx.headrevs())

    def test_get_cindex(self):
        # drop me once we no longer need the method for shortest node
        idx = self.parseindex()
        rustidx = revlog.MixedIndex(idx)
        cidx = rustidx.get_cindex()
        self.assertTrue(idx is cidx)

    def test_len(self):
        idx = self.parseindex()
        rustidx = revlog.MixedIndex(idx)
        self.assertEqual(len(rustidx), len(idx))

    def test_ancestors(self):
        idx = self.parseindex()
        rustidx = revlog.MixedIndex(idx)
        lazy = LazyAncestors(rustidx, [3], 0, True)
        # we have two more references to the index:
        # - in its inner iterator for __contains__ and __bool__
        # - in the LazyAncestors instance itself (to spawn new iterators)
        self.assertTrue(2 in lazy)
        self.assertTrue(bool(lazy))
        self.assertEqual(list(lazy), [3, 2, 1, 0])
        # a second time to validate that we spawn new iterators
        self.assertEqual(list(lazy), [3, 2, 1, 0])

        # let's check bool for an empty one
        self.assertFalse(LazyAncestors(idx, [0], 0, False))


if __name__ == '__main__':
    import silenttestrunner

    silenttestrunner.main(__name__)