Eric Appelt added the comment: I added a PR to fix these two (in my opinion) spurious failure conditions in the lib2to3.tests.test_parser.TestParserIdempotency test_parser test with the following changes to the test:
1. Use the same encoding found in the initial file to write a temp file for a diff. This retains the BOM if the encoding was initially utf-8-sig. 2. If the file cannot be parsed using the normal grammar, try again with no print statement which should succeed for valid files using future print_function For case (1), the driver was correctly handling a BOM in a utf-8 file, but then the test was not writing a comparison file using 'utf-8-sig' to diff against, so the BOM got removed. I don't think that is the fault of the parser, and lib2to3 will retain the BOM. For case (2), lib2to3 pre-detects the use of from __future__ import print_function or allows the user to force this interpretation with a -p flag, and then selects a different grammar with the print statement removed. That makes the test cases unfair to this test as the driver itself doesn't know which grammar to use. As a minimal fix, the test will try using a grammar with the print statement, and if that fails fall back on a grammar without it. A more thorough handling of the idempotency test would to be to parse all files using both grammars and ignore if one of the two failed but otherwise check both. I didn't think this was necessary but can change. ---------- nosy: +Eric Appelt _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue30117> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
