[Python-Dev] fixing tests on windows

[Neal Norwitz]

The Windows buildbots are still failing because some tests keep files
opened.  This causes subsequent tests which use the same file to fail.

Here is a recent run which had a failure early on:
http://www.python.org/dev/buildbot/stable/x86%20XP-3%20trunk/builds/1209/step-test/0

I'm assuming the first failure (test_bufio) was due to an open file.
(Can't tell, no error msg.)  That means the problem was in that test
or an earlier test.  The only earlier tests are:

test_import
test_sys
test_descr
test_xdrlib
test_urllibnet
test_binhex
test_strptime
test_importhooks
test_copy
test_hmac
test_genericpath
test_complex
test_timeout
test_quopri
test_marshal
test_zipfile
test_mutants
test_csv
test_ucn
test_hash
test_wsgiref
test_mmap
test_ftplib
test_pickletools
test_codecmaps_cn

Of those tests, only some of them reference TESTFN which is the probable file:

test_import 22
test_descr 3
test_urllibnet 2
test_binhex 2
test_genericpath 44
test_complex 3
test_marshal 33
test_zipfile 136
test_mutants 7
test_mmap 32

I inspected test_mmap which had been modified somewhat recently and
tried to fix a few things.  I'm not sure I helped and there are
probably more problems lurking.

This issue may not be noticed in the default test run.  It definitely
occurs when the tests are run in a random order as they are on the
buildbots.  Try running:  ./python.exe ./Lib/test/regrtest.py -r

That should help provoke more errors.

As always, patches are greatly appreciated.

Cheers,
n