Here's the revision that broke it: b81ddaf0db47

The 2.7 branch still uses imp.get_suffixes, whereas the 3.3 and 3.4 uses this importlib construct.

The imp.get_suffixes returns a list of tuples of 3 items: (suffix, mode, type). The current code only returns what would be the first item of that tuple. The for-loop only uses that first item anyway, so the tuple unpacking can be removed safely.


The attached patch fixes the issue. It also includes a basic unit test within the idlelib/test directory. We need to get the unittest framework started for IDLE, as given in issue15392.