======================================================================                   [1633/2616]
ERROR: test_link (test.test_os.LinkTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/sdcard/org.bitbucket.pyona/lib/python3.7/test/test_os.py", line 1703, in test_link
    self._test_link(self.file1, self.file2)
  File "/sdcard/org.bitbucket.pyona/lib/python3.7/test/test_os.py", line 1698, in _test_link
    os.link(file1, file2)
PermissionError: [Errno 13] Permission denied: '@test_2295_tmp' -> '@test_2295_tmp2'

======================================================================
ERROR: test_link_bytes (test.test_os.LinkTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/sdcard/org.bitbucket.pyona/lib/python3.7/test/test_os.py", line 1707, in test_link_bytes
    bytes(self.file2, sys.getfilesystemencoding()))
  File "/sdcard/org.bitbucket.pyona/lib/python3.7/test/test_os.py", line 1698, in _test_link
    os.link(file1, file2)
PermissionError: [Errno 13] Permission denied: b'@test_2295_tmp' -> b'@test_2295_tmp2'

======================================================================
ERROR: test_unicode_name (test.test_os.LinkTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/sdcard/org.bitbucket.pyona/lib/python3.7/test/test_os.py", line 1717, in test_unicode_name
    self._test_link(self.file1, self.file2)
  File "/sdcard/org.bitbucket.pyona/lib/python3.7/test/test_os.py", line 1698, in _test_link
    os.link(file1, file2)
PermissionError: [Errno 13] Permission denied: '@test_2295_tmpñ' -> '@test_2295_tmpñ2'

======================================================================
ERROR: test_stty_match (test.test_os.TermsizeTests)
Check if stty returns the same results
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/sdcard/org.bitbucket.pyona/lib/python3.7/test/test_os.py", line 2795, in test_stty_match
    size = subprocess.check_output(['stty', 'size']).decode().split()
  File "/sdcard/org.bitbucket.pyona/lib/python3.7/subprocess.py", line 336, in check_output
    **kwargs).stdout
  File "/sdcard/org.bitbucket.pyona/lib/python3.7/subprocess.py", line 403, in run
    with Popen(*popenargs, **kwargs) as process:
  File "/sdcard/org.bitbucket.pyona/lib/python3.7/subprocess.py", line 707, in __init__
    restore_signals, start_new_session)
  File "/sdcard/org.bitbucket.pyona/lib/python3.7/subprocess.py", line 1323, in _execute_child
    raise child_exception_type(errno_num, err_msg)
PermissionError: [Errno 13] Permission denied

======================================================================
ERROR: test_attributes (test.test_os.TestScandir)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/sdcard/org.bitbucket.pyona/lib/python3.7/test/test_os.py", line 3150, in test_attributes
    os.link(filename, os.path.join(self.path, "link_file.txt"))
PermissionError: [Errno 13] Permission denied: '/data/local/tmp/test_python_2295/@test_2295_tmp/file
.txt' -> '/data/local/tmp/test_python_2295/@test_2295_tmp/link_file.txt'

----------------------------------------------------------------------
Ran 238 tests in 4.675s

FAILED (errors=5, skipped=40)
test test_os failed

Patch attached.

Are you planning to use test.support.os_link() to fix other tests in near future? If test_os is the only user of the helper, I'd say let's keep it in Lib/test/test_os.py for now. test.support is already big enough and it would be better not to put every snippet in it :)

If there are other tests that can benefit from using it, the patch looks good to me.

> If test_os is the only user of the helper, I'd say let's keep it in Lib/test/test_os.py for now.

I agree with that concern.

support.os_link() is also used by a patch in issue 29181, and I am planning to modify the changes made by issue 28759 to also use it so that tests calling os.link() are skipped based on the fact that they raise PermissionError instead of based on the fact that they are being run by an Android non-root user as is currently the case.

New patch following Serhiy's suggestion in msg285008.

New changeset 6a55d09573e5c35c9e4a24a6f811120b41a2a994 by xdegaye in branch 'master':
bpo-29180: Skip test_os tests on PermissionError raised by Android (GH-4374)
https://github.com/python/cpython/commit/6a55d09573e5c35c9e4a24a6f811120b41a2a994