Check for empty sections in environment

Passing empty section like parameters in the environment can leave the
user with a strange error message. This fixes the issue by providing a
correct error.

Change-Id: I766cd38e8a70c9f76cf10f540e22a929eaed3768
Closes-Bug: #1606148

heat/api/openstack/v1/stacks.py

@@ -138,10 +138,10 @@ class InstantiationData(object):
         env = {}
         if self.PARAM_ENVIRONMENT in self.data:
             env_data = self.data[self.PARAM_ENVIRONMENT]
-            if isinstance(env_data, dict):
-                env = env_data
-            else:
-                with self.parse_error_check('Environment'):
+            with self.parse_error_check('Environment'):
+                if isinstance(env_data, dict):
+                    env = environment_format.validate(env_data)
+                else:
                     env = environment_format.parse(env_data)
 
         environment_format.default_for_missing(env)

heat/common/environment_format.py

@@ -1,4 +1,3 @@
-#
 #    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
@@ -48,9 +47,15 @@ def parse(env_str):
     if not isinstance(env, dict):
         raise ValueError(_('The environment is not a valid '
                            'YAML mapping data type.'))
+    return validate(env)
+
+
+def validate(env):
     for param in env:
         if param not in SECTIONS:
             raise ValueError(_('environment has wrong section "%s"') % param)
+        if env[param] is None:
+            raise ValueError(_('environment has empty section "%s"') % param)
 
     return env
 

heat/tests/api/openstack_v1/test_stacks.py

@@ -195,6 +195,12 @@ blarg: wibble
         data = stacks.InstantiationData(body)
         self.assertEqual(expect, data.environment())
 
+    def test_environment_empty_params(self):
+        env = {'parameters': None}
+        body = {'environment': env}
+        data = stacks.InstantiationData(body)
+        self.assertRaises(webob.exc.HTTPBadRequest, data.environment)
+
     def test_environment_bad_format(self):
         env = {'somethingnotsupported': {'blarg': 'wibble'}}
         body = {'environment': json.dumps(env)}