tests/test-util.py

typing: attempt to remove @overloads in the platform module for stdlib methods

This is mostly successful, as examining util.pyi, posix.pyi, and windows.pyi
after a pytype run shows that the type overloads for `oslink`, `readlink`,
`removedirs`, `rename`, `split`, and `unlink` have been removed.  (Some of these
still have an @overload, but the differences are the variable names, not the
types.)  However, @overloads remain for `abspath` and `normpath` for some
reason.

It's useful to redefine these methods for the type checking phase because in
addition to excluding str and PathLike variants, some of these functions have
optional args in stdlib that aren't implemented in the custom implementation on
Windows, and we want the type checking to flag that instead of assuming it's an
allowable overload everywhere.

One last quirk I noticed that I can't explain- `pycompat.TYPE_CHECKING` is
always False, so the conditionals need to check `typing.TYPE_CHECKING` directly.
I tried dropping the custom code for assigning `pycompat.TYPE_CHECKING` and
simply did `from typing import TYPE_CHECKING` directly in pycompat.py, and used
`pycompat.TYPE_CHECKING` for the conditional here... and pytype complained that
`pycompat` doesn't have the `TYPE_CHECKING` variable.

# unit tests for mercuril.util utilities

import contextlib
import io
import itertools
import unittest

from mercurial import pycompat, util, utils


@contextlib.contextmanager
def mocktimer(incr=0.1, *additional_targets):
    """Replaces util.timer and additional_targets with a mock

    The timer starts at 0. On each call the time incremented by the value
    of incr. If incr is an iterable, then the time is incremented by the
    next value from that iterable, looping in a cycle when reaching the end.

    additional_targets must be a sequence of (object, attribute_name) tuples;
    the mock is set with setattr(object, attribute_name, mock).

    """
    time = [0]
    try:
        incr = itertools.cycle(incr)
    except TypeError:
        incr = itertools.repeat(incr)

    def timer():
        time[0] += next(incr)
        return time[0]

    # record original values
    orig = util.timer
    additional_origs = [(o, a, getattr(o, a)) for o, a in additional_targets]

    # mock out targets
    util.timer = timer
    for obj, attr in additional_targets:
        setattr(obj, attr, timer)

    try:
        yield
    finally:
        # restore originals
        util.timer = orig
        for args in additional_origs:
            setattr(*args)


# attr.s default factory for util.timedstats.start binds the timer we
# need to mock out.
_start_default = (util.timedcmstats.__attrs_attrs__.start.default, 'factory')


@contextlib.contextmanager
def capturestderr():
    """Replace utils.procutil.stderr with an io.BytesIO instance

    The instance is made available as the return value of __enter__.

    This contextmanager is reentrant.

    """
    orig = utils.procutil.stderr
    utils.procutil.stderr = io.BytesIO()
    try:
        yield utils.procutil.stderr
    finally:
        utils.procutil.stderr = orig


class timedtests(unittest.TestCase):
    def testtimedcmstatsstr(self):
        stats = util.timedcmstats()
        self.assertEqual(str(stats), '<unknown>')
        self.assertEqual(bytes(stats), b'<unknown>')
        stats.elapsed = 12.34
        self.assertEqual(str(stats), pycompat.sysstr(util.timecount(12.34)))
        self.assertEqual(bytes(stats), util.timecount(12.34))

    def testtimedcmcleanexit(self):
        # timestamps 1, 4, elapsed time of 4 - 1 = 3
        with mocktimer([1, 3], _start_default):
            with util.timedcm('pass') as stats:
                # actual context doesn't matter
                pass

        self.assertEqual(stats.start, 1)
        self.assertEqual(stats.elapsed, 3)
        self.assertEqual(stats.level, 1)

    def testtimedcmnested(self):
        # timestamps 1, 3, 6, 10, elapsed times of 6 - 3 = 3 and 10 - 1 = 9
        with mocktimer([1, 2, 3, 4], _start_default):
            with util.timedcm('outer') as outer_stats:
                with util.timedcm('inner') as inner_stats:
                    # actual context doesn't matter
                    pass

        self.assertEqual(outer_stats.start, 1)
        self.assertEqual(outer_stats.elapsed, 9)
        self.assertEqual(outer_stats.level, 1)

        self.assertEqual(inner_stats.start, 3)
        self.assertEqual(inner_stats.elapsed, 3)
        self.assertEqual(inner_stats.level, 2)

    def testtimedcmexception(self):
        # timestamps 1, 4, elapsed time of 4 - 1 = 3
        with mocktimer([1, 3], _start_default):
            try:
                with util.timedcm('exceptional') as stats:
                    raise ValueError()
            except ValueError:
                pass

        self.assertEqual(stats.start, 1)
        self.assertEqual(stats.elapsed, 3)
        self.assertEqual(stats.level, 1)

    def testtimeddecorator(self):
        @util.timed
        def testfunc(callcount=1):
            callcount -= 1
            if callcount:
                testfunc(callcount)

        # timestamps 1, 2, 3, 4, elapsed time of 3 - 2 = 1 and 4 - 1 = 3
        with mocktimer(1, _start_default):
            with capturestderr() as out:
                testfunc(2)

        self.assertEqual(
            out.getvalue(),
            (b'    testfunc: 1.000 s\n' b'  testfunc: 3.000 s\n'),
        )


if __name__ == '__main__':
    import silenttestrunner

    silenttestrunner.main(__name__)