Instead of using full, real data files for the unit tests, you should devise a couple of very simple OTU map files and drop them at the bottom of this file (see tests/test_utils.py for how I'm doing this with mapping files, OTU maps, etc.). This is advantageous because the unit tests will run quicker, you can devise your test "files" to hit explicit edge cases, and it isn't relying on external files existing in a specific location (for example, these unit tests won't work if you run ```nosetests``` anywhere but from within the root directory of the fresco repository).