Enable hacking rule F821

F821: undefined name

Currently, we define global variables at runtime in
keystoneclient/tests/test_shell.py, which cannot detected by hacking
rule check, then it fails for rule F821.

This patch changes the global lambda shell to a helper function.

Change-Id: Iaf5c4e40a6b17fbf4ba0c254b75d347f08b52364

keystoneclient/tests/test_shell.py

@@ -37,6 +37,11 @@ DEFAULT_TENANT_NAME = 'tenant_name'
 DEFAULT_AUTH_URL = 'http://127.0.0.1:5000/v2.0/'
 
 
+# Make a fake shell object, a helping wrapper to call it
+def shell(cmd):
+    openstack_shell.OpenStackIdentityShell().main(cmd.split())
+
+
 class NoExitArgumentParser(argparse.ArgumentParser):
     def error(self, message):
         raise exceptions.CommandError(message)
@@ -68,12 +73,6 @@ class ShellTest(utils.TestCase):
             self.useFixture(fixtures.EnvironmentVariable(var,
                             self.FAKE_ENV[var]))
 
-        # Make a fake shell object, a helping wrapper to call it, and a quick
-        # way of asserting that certain API calls were made.
-        global shell, _shell, assert_called, assert_called_anytime
-        _shell = openstack_shell.OpenStackIdentityShell()
-        shell = lambda cmd: _shell.main(cmd.split())
-
     def test_help_unknown_command(self):
         self.assertRaises(exceptions.CommandError, shell, 'help %s'
                           % uuid.uuid4().hex)

tox.ini

@@ -31,12 +31,11 @@ downloadcache = ~/cache/pip
 commands = oslo_debug_helper -t keystoneclient/tests {posargs}
 
 [flake8]
-# F821: undefined name
 # H304: no relative imports
 # H405: multi line docstring summary not separated with an empty line
 # E122: continuation line missing indentation or outdented
 # New from hacking 0.10: H238
-ignore = F821,H238,H304,H405,E122
+ignore = H238,H304,H405,E122
 show-source = True
 exclude = .venv,.tox,dist,doc,*egg,build,*openstack/common*