Recognize __module__ when used in class scope

Fixes #259.

Author: mgedmin

pyflakes/checker.py

@@ -756,6 +756,9 @@ def handleNodeLoad(self, node):
             # the special name __path__ is valid only in packages
             return
 
+        if name == '__module__' and isinstance(self.scope, ClassScope):
+            return
+
         # protected with a NameError handler?
         if 'NameError' not in self.exceptHandlers[-1]:
             self.report(messages.UndefinedName, node, name)

pyflakes/test/test_undefined_names.py

@@ -256,6 +256,22 @@ def test_magicGlobalsPath(self):
         self.flakes('__path__', m.UndefinedName)
         self.flakes('__path__', filename='package/__init__.py')
 
+    def test_magicModuleInClassScope(self):
+        """
+        Use of the C{__module__} magic builtin should not emit an undefined
+        name warning if used in class scope.
+        """
+        self.flakes('__module__', m.UndefinedName)
+        self.flakes('''
+        class Foo:
+            __module__
+        ''')
+        self.flakes('''
+        class Foo:
+            def bar(self):
+                __module__
+        ''', m.UndefinedName)
+
     def test_globalImportStar(self):
         """Can't find undefined names with import *."""
         self.flakes('from fu import *; bar',