Some of the tests for lib2to3 write into folders which are protected in an installed Python. This means that regression tests fail when run on an installed Python, even though they run wihtout these errors on a source build. I think writes should be done into temp files, so that you can run regressions on installed Pythons.

Example failure:

======================================================================
ERROR: test_refactor_file (lib2to3.tests.test_refactor.TestRefactoringTool)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/local/lib/python3.3/lib2to3/tests/test_refactor.py", line 190, in check_file_refactoring
    rt.refactor_file(test_file, True)
  File "/usr/local/lib/python3.3/lib2to3/refactor.py", line 353, in refactor_file
    write=write, encoding=encoding)
  File "/usr/local/lib/python3.3/lib2to3/refactor.py", line 518, in processed_file
    self.write_file(new_text, filename, old_text, encoding)
  File "/usr/local/lib/python3.3/lib2to3/refactor.py", line 530, in write_file
    f = _open_with_encoding(filename, "w", encoding=encoding)
IOError: [Errno 13] Permission denied: '/usr/local/lib/python3.3/lib2to3/tests/data/fixers/parrot_example.py'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.3/lib2to3/tests/test_refactor.py", line 200, in test_refactor_file
    self.check_file_refactoring(test_file, _DEFAULT_FIXERS)
  File "/usr/local/lib/python3.3/lib2to3/tests/test_refactor.py", line 194, in check_file_refactoring
    with open(test_file, "wb") as fp:
IOError: [Errno 13] Permission denied: '/usr/local/lib/python3.3/lib2to3/tests/data/fixers/parrot_example.py'

Some packaging tests also fail, for similar reasons:

======================================================================
ERROR: test_get_distinfo_file (packaging.tests.test_database.TestDistribution)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/local/lib/python3.3/packaging/tests/test_database.py", line 114, in setUp
    with open(record_file, 'w') as file:
IOError: [Errno 13] Permission denied: '/usr/local/lib/python3.3/packaging/tests/fake_dists/babar-0.1.dist-info/RECORD'

This should not be too hard to fix: I’ll move the directory with the mock projects to a temp dir, add that to sys.path, and then we’ll be able to read and write.

problem exists in python 2.7.2 (should this be reported as a separate issue?)

[Python-2.7.2]$ python -m test.regrtest  -v test_lib2to3
...
ERROR: test_bom (lib2to3.tests.test_refactor.TestRefactoringTool)
...
ERROR: test_crlf_newlines 
ERROR: test_file_encoding
ERROR: test_refactor_file
...

e.g.,

  File "/usr/local/lib/python2.7/lib2to3/tests/test_refactor.py", line 194, in check_file_refactoring
    with open(test_file, "wb") as fp:
IOError: [Errno 13] Permission denied: '/usr/local/lib/python2.7/lib2to3/tests/data/fixers/parrot_example.py'
...
[test]# ls -l /usr/local/lib/python2.7/lib2to3/tests/data/fixers/parrot_example.py 
-rw-r--r-- 1 root root 23 2011-07-23 11:48 /usr/local/lib/python2.7/lib2to3/tests/data/fixers/parrot_example.py

New changeset 2b5a0c4e052b by Éric Araujo in branch '3.2':
Stop trying to write into the stdlib during lib2to3 tests (#12331).
http://hg.python.org/cpython/rev/2b5a0c4e052b

New changeset 7ee8f413188e by Éric Araujo in branch 'default':
Stop trying to write into the stdlib during packaging tests (#12331).
http://hg.python.org/cpython/rev/7ee8f413188e

New changeset a425408f1e52 by Éric Araujo in branch '2.7':
Stop trying to write into the stdlib during lib2to3 tests (#12331).
http://hg.python.org/cpython/rev/a425408f1e52

This is now fixed.  Let me just eat these words: “This should not be too hard to fix”.