Document purpose

test_fuzz.py

@@ -1,6 +1,12 @@
 #!/usr/bin/env python
 
-"""Test that autoflake runs without crashing on arbitrary Python files."""
+"""Test that autoflake performs correctly on arbitrary Python files.
+
+This checks that autoflake never introduces incorrect syntax. This is
+done by doing a syntax check after the autoflake run. The number of
+Pyflakes warnings is also confirmed to always improve.
+
+"""
 
 from __future__ import print_function
 from __future__ import unicode_literals