catch IOError in subprocess_supports_unicode

[wiggin15]

When running the unit tests on macOS (10.13.6), I get this:

...
rm -rf tmp
PYTHONWARNINGS=all PSUTIL_TESTING=1 PSUTIL_DEBUG=1 python psutil/tests/__main__.py
Traceback (most recent call last):
  File "psutil/tests/__main__.py", line 94, in <module>
    main()
  File "psutil/tests/__main__.py", line 91, in main
    run_suite()
  File "/Users/arnony/git/external/psutil/psutil/tests/__init__.py", line 841, in run_suite
    result = unittest.TextTestRunner(verbosity=VERBOSITY).run(get_suite())
  File "/Users/arnony/git/external/psutil/psutil/tests/__init__.py", line 835, in get_suite
    suite.addTest(unittest.defaultTestLoader.loadTestsFromName(tm))
  File "/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/unittest/loader.py", line 91, in loadTestsFromName
    module = __import__('.'.join(parts_copy))
  File "/Users/arnony/git/external/psutil/psutil/tests/test_unicode.py", line 310, in <module>
    @unittest.skipIf(not subprocess_supports_unicode(INVALID_NAME),
  File "/Users/arnony/git/external/psutil/psutil/tests/test_unicode.py", line 120, in subprocess_supports_unicode
    create_exe(name)
  File "/Users/arnony/git/external/psutil/psutil/tests/__init__.py", line 783, in create_exe
    shutil.copyfile(PYTHON_EXE, outpath)
  File "/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 83, in copyfile
    with open(dst, 'wb') as fdst:
IOError: [Errno 92] Illegal byte sequence: '/Users/arnony/git/external/psutil/@psutil-test-46016f\xc0\x80'
executing cleanup_test_procs() atexit function
executing cleanup_test_files() atexit function
removing temporary test file u'@psutil-test-46016-\xc6\x92\xc5\x91\xc5\x91'
make: *** [test] Error 1

subprocess_supports_unicode should return False when the filesystem does not support the given name (INVALID_NAME in this case)

[giampaolo]

How about this instead?

--- a/psutil/tests/test_unicode.py
+++ b/psutil/tests/test_unicode.py
@@ -115,6 +115,20 @@ def subprocess_supports_unicode(name):
     """
     if PY3:
         return True
+
+    if MACOS:
+        try:
+            with open(name, 'wb'):
+                pass
+        except IOError as err:
+            if err.errno == errno.EILSEQ:
+                return False
+            raise
+
     try:
         safe_rmpath(name)
         create_exe(name)

[wiggin15]

Do you think we should be this specific? What if we can get other kinds of IOError or IOErrors on other operating systems - the same underlying issue can manifest in different ways and we should always behave the same, no?

[giampaolo]

I have the feeling this an error which will occur on MACOS only. Or maybe not, but in that case we'll just get rid of the if MACOS: part and make it more generic. I think this is too broad:

try:
    safe_rmpath(name)
    create_exe(name)
    get_test_subprocess(cmd=[name])
except (UnicodeEncodeError, IOError):    
    return False

...because you're covering 3 different calls, and a lot is going on in each one of them. Catching UnicodeEncodeError is fine in this case, because that's exactly what you're looking for, but IOError is not what you're looking for. E.g. in case of IOError(EACCES) you want that exception to bubble up instead of returning False.