view tests/test-atomictempfile.py @ 47315:825d5a5907b4

exewrapper: avoid directly linking against python3X.dll

Subsequent code calls `LoadLibrary()` to attempt to load the DLL, but because of
this symbol reference, there is an attempt to load the DLL used during the build
prior to `_main()` running.  This causes the whole process to fail if the DLL
isn't in the standard search path.  That also means it will never load the DLL
for HackableMercurial.  (Maybe we should get rid of that for py3, since you can
install python for a user without admin rights?)

This could also be resolved by calling `GetProcAddress()` on the symbol and
dereferencing it, but using the environment variable is consistent with the
*.bat file since fc8a5c9ecee0.  (The environment variable persists after the
interpreter is initialized.)

Far more concerning is somehow I've gotten my system into a state where setting
the flag causes any output to the pager to be lost (as if it wasn't set at all)
in MSYS, cmd.exe, WSL, and PowerShell using py3.9.0, but the environment
variable works properly.  I'm sure this flag worked on some versions of py3, so
I'm not sure what's going on here.  This is might be related to init config
related changes in 3.8[1], since it works with 3.7.8, but fails with 3.8.1.
Somebody who understands encoding issues better than I do should give some
thought to if we need to make some changes to our encoding strategy on Windows
with py3.

With or without the flag/envvar, there is proper output if the command is
directly paged by piping to `more.com` (in any environment) or `less` (in MSYS
and WSL), or if paging is disabled with `--pager=no`.  Legacy mode is required
though when Mercurial decides to spin up a pager.

[1] https://bugs.python.org/issue41941

Differential Revision: https://phab.mercurial-scm.org/D10756

from __future__ import absolute_import

import glob
import os
import shutil
import stat
import tempfile
import unittest

from mercurial import (
    pycompat,
    util,
)

atomictempfile = util.atomictempfile

if pycompat.ispy3:
    xrange = range


class testatomictempfile(unittest.TestCase):
    def setUp(self):
        self._testdir = tempfile.mkdtemp(b'atomictempfiletest')
        self._filename = os.path.join(self._testdir, b'testfilename')

    def tearDown(self):
        shutil.rmtree(self._testdir, True)

    def testsimple(self):
        file = atomictempfile(self._filename)
        self.assertFalse(os.path.isfile(self._filename))
        tempfilename = file._tempname
        self.assertTrue(
            tempfilename
            in glob.glob(os.path.join(self._testdir, b'.testfilename-*'))
        )

        file.write(b'argh\n')
        file.close()

        self.assertTrue(os.path.isfile(self._filename))
        self.assertTrue(
            tempfilename
            not in glob.glob(os.path.join(self._testdir, b'.testfilename-*'))
        )

    # discard() removes the temp file without making the write permanent
    def testdiscard(self):
        file = atomictempfile(self._filename)
        (dir, basename) = os.path.split(file._tempname)

        file.write(b'yo\n')
        file.discard()

        self.assertFalse(os.path.isfile(self._filename))
        self.assertTrue(basename not in os.listdir(b'.'))

    # if a programmer screws up and passes bad args to atomictempfile, they
    # get a plain ordinary TypeError, not infinite recursion
    def testoops(self):
        with self.assertRaises(TypeError):
            atomictempfile()

    # checkambig=True avoids ambiguity of timestamp
    def testcheckambig(self):
        def atomicwrite(checkambig):
            f = atomictempfile(self._filename, checkambig=checkambig)
            f.write(b'FOO')
            f.close()

        # try some times, because reproduction of ambiguity depends on
        # "filesystem time"
        for i in xrange(5):
            atomicwrite(False)
            oldstat = os.stat(self._filename)
            if oldstat[stat.ST_CTIME] != oldstat[stat.ST_MTIME]:
                # subsequent changing never causes ambiguity
                continue

            repetition = 3

            # repeat atomic write with checkambig=True, to examine
            # whether st_mtime is advanced multiple times as expected
            for j in xrange(repetition):
                atomicwrite(True)
            newstat = os.stat(self._filename)
            if oldstat[stat.ST_CTIME] != newstat[stat.ST_CTIME]:
                # timestamp ambiguity was naturally avoided while repetition
                continue

            # st_mtime should be advanced "repetition" times, because
            # all atomicwrite() occurred at same time (in sec)
            oldtime = (oldstat[stat.ST_MTIME] + repetition) & 0x7FFFFFFF
            self.assertTrue(newstat[stat.ST_MTIME] == oldtime)
            # no more examination is needed, if assumption above is true
            break
        else:
            # This platform seems too slow to examine anti-ambiguity
            # of file timestamp (or test happened to be executed at
            # bad timing). Exit silently in this case, because running
            # on other faster platforms can detect problems
            pass

    def testread(self):
        with open(self._filename, 'wb') as f:
            f.write(b'foobar\n')
        file = atomictempfile(self._filename, mode=b'rb')
        self.assertTrue(file.read(), b'foobar\n')
        file.discard()

    def testcontextmanagersuccess(self):
        """When the context closes, the file is closed"""
        with atomictempfile(b'foo') as f:
            self.assertFalse(os.path.isfile(b'foo'))
            f.write(b'argh\n')
        self.assertTrue(os.path.isfile(b'foo'))

    def testcontextmanagerfailure(self):
        """On exception, the file is discarded"""
        try:
            with atomictempfile(b'foo') as f:
                self.assertFalse(os.path.isfile(b'foo'))
                f.write(b'argh\n')
                raise ValueError
        except ValueError:
            pass
        self.assertFalse(os.path.isfile(b'foo'))


if __name__ == '__main__':
    import silenttestrunner

    silenttestrunner.main(__name__)