hacking log warn

LOG.warn is deprecated in Python 3 [1], so add hacking warn.
[1]https://docs.python.org/3/library/logging.html#logging.warning

Change-Id: I95aa121c2b11437a086d7f8bee25ffa956dd3e4f

heat/hacking/checks.py

@@ -0,0 +1,29 @@
+# Copyright (c) 2016 OpenStack Foundation
+# All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+
+def no_log_warn(logical_line):
+    """Disallow 'LOG.warn('
+
+    https://bugs.launchpad.net/tempest/+bug/1508442
+
+    H001
+    """
+    if logical_line.startswith('LOG.warn('):
+        yield(0, 'H001 Use LOG.warning() rather than LOG.warn()')
+
+
+def factory(register):
+    register(no_log_warn)

tox.ini

@@ -68,6 +68,7 @@ max-complexity=20
 
 [hacking]
 import_exceptions = heat.common.i18n
+local-check-factory = heat.hacking.checks.factory
 
 [testenv:debug]
 commands = oslo_debug_helper {posargs}