Add pyflakes

Add ability to use pyflakes to tox.ini

Change-Id: If334cb1ac64a5fe7aabb17af0048a20aa2cdd921
Signed-off-by: Chuck Short <chuck.short@canonical.com>

tools/flakes.py

@@ -0,0 +1,22 @@
+"""
+ wrapper for pyflakes to ignore gettext based warning:
+     "undefined name '_'"
+
+ From https://bugs.launchpad.net/pyflakes/+bug/844592
+"""
+import __builtin__
+import os
+import sys
+
+from pyflakes.scripts.pyflakes import main
+
+if __name__ == "__main__":
+    names = os.environ.get('PYFLAKES_BUILTINS', '_')
+    names = [x.strip() for x in names.split(',')]
+    for x in names:
+        if not hasattr(__builtin__, x):
+            setattr(__builtin__, x, True)
+
+    del names, os, __builtin__
+
+    sys.exit(main())

tox.ini

@@ -36,3 +36,7 @@ deps = -r{toxinidir}/tools/test-requires-folsom
 [testenv:py27-folsom]
 deps = -r{toxinidir}/tools/test-requires-folsom
        -r{toxinidir}/tools/pip-requires
+
+[testenv:pyflakes]
+deps = pyflakes
+commands = python tools/flakes.py ceilometer