Allow DependsOn to accept a list

http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-attribute-dependson.html

Change-Id: I8187d8a0395cc96d9727aa812d57f281e69c516d
Closes-bug: #1235496

2 files changed, 37 insertions, 10 deletions

diff --git a/heat/engine/resource.py b/heat/engine/resource.py
index 1141b008c..4fd11801d 100644
--- a/heat/engine/resource.py
+++ b/heat/engine/resource.py
@@ -284,16 +284,22 @@ class Resource(object):
                 if key in ('DependsOn', 'Ref', 'Fn::GetAtt', 'get_attr',
                            'get_resource'):
                     if key in ('Fn::GetAtt', 'get_attr'):
-                        value, att = value
-
-                    try:
-                        target = self.stack.resources[value]
-                    except KeyError:
-                        raise exception.InvalidTemplateReference(
-                            resource=value,
-                            key=path)
-                    if key == 'DependsOn' or target.strict_dependency:
-                        deps += (self, target)
+                        res_name, att = value
+                        res_list = [res_name]
+                    elif key == 'DependsOn' and isinstance(value, list):
+                        res_list = value
+                    else:
+                        res_list = [value]
+
+                    for res in res_list:
+                        try:
+                            target = self.stack[res]
+                        except KeyError:
+                            raise exception.InvalidTemplateReference(
+                                resource=res,
+                                key=path)
+                        if key == 'DependsOn' or target.strict_dependency:
+                            deps += (self, target)
                 else:
                     self._add_dependencies(deps, '%s.%s' % (path, key), value)
         elif isinstance(fragment, list):
diff --git a/heat/tests/test_parser.py b/heat/tests/test_parser.py
index 5b9789042..9ac90f9ff 100644
--- a/heat/tests/test_parser.py
+++ b/heat/tests/test_parser.py
@@ -1798,6 +1798,27 @@ class StackTest(HeatTestCase):
             self.assertIn(r, required_by)
 
     @utils.stack_delete_after
+    def test_resource_multi_required_by(self):
+        tmpl = {'Resources': {'AResource': {'Type': 'GenericResourceType'},
+                              'BResource': {'Type': 'GenericResourceType'},
+                              'CResource': {'Type': 'GenericResourceType'},
+                              'DResource': {'Type': 'GenericResourceType',
+                                            'DependsOn': ['AResource',
+                                                          'BResource',
+                                                          'CResource']}}}
+
+        self.stack = parser.Stack(self.ctx, 'depends_test_stack',
+                                  template.Template(tmpl))
+        self.stack.store()
+        self.stack.create()
+        self.assertEqual(self.stack.state,
+                         (parser.Stack.CREATE, parser.Stack.COMPLETE))
+
+        for r in ['AResource', 'BResource', 'CResource']:
+            self.assertEqual(['DResource'],
+                             self.stack[r].required_by())
+
+    @utils.stack_delete_after
     def test_store_saves_owner(self):
         """
         The owner_id attribute of Store is saved to the database when stored.