Add checker for local variables inside functions

Do not signal globals as local variables

pep8.py

@@ -1251,6 +1251,32 @@ def visit_importfrom(self, node, parents):
                 self.error_at_node(node, self.W803)
 
 
+class VariablesInFunctionsASTCheck(BaseAstCheck):
+    """
+    Local variables in functions should be in lowercase
+    """
+    LOWER_CASE = re.compile('[a-z][a-z0-9_]*$').match
+    E805 = "E805 Variables in functions should be lowercase"
+
+    def visit_assign(self, node, parents):
+        parent_func = self.get_parent_function(parents)
+        if parent_func is None:
+            return
+
+        for name in self._get_target_names(node):
+            if name in parent_func.global_names:
+                return
+            if not self.LOWER_CASE(name):
+                self.error_at_node(node, self.E805)
+
+    def _get_target_names(self, node):
+        targets = set()
+        for target in node.targets:
+            if isinstance(target, ast.Name):
+                targets.add(target.id)
+        return targets
+
+
 ##############################################################################
 # Helper functions
 ##############################################################################

testsuite/E85.py

@@ -0,0 +1,34 @@
+#: Okay
+def test():
+    good = 1
+#: Okay
+def test():
+    def test2():
+        good = 1
+#: Okay
+GOOD = 1
+#: Okay
+class Test(object):
+    GOOD = 1
+#: E805
+def test():
+    Bad = 1
+#: E805
+def test():
+    VERY = 2
+#: E805
+def test():
+    def test2():
+        class Foo(object):
+            def test3(self):
+                Bad = 3
+#: Okay
+def good():
+    global Bad
+    Bad = 1
+#: E805
+def bad():
+    global Bad
+
+    def foo():
+        Bad = 1