drj11/pypng — pull request #8 by e98cuenc (2012-09-20 14:41:02+00:00)
Title: Add tests to cover the filter and unfilter methods.

I want to optimize these methods, so I first implemented some unittests to prevent regressions.

I think I discovered a bug in the "up" filter of the a line without a previous line, please take a look at test_filter_scanline_first_line because I'm not 100% sure it's actually a bug.