Fix ResourceGroup validate when there are removal_policies

We can't call child_template() from a validate in ResourceGroup
as it accesses nested(). So move the validation to validate_nested_stack()
so we can control the test template used for validation.

Unfortunately coverage for this got removed during recent test rework
and it looks like the interface has got broken.

Co-Authored-by: Angus Salkeld <asalkeld@mirantis.com>
Change-Id: Ibea738a343847736b041cc49a2c486fa71e562d9
Closes-Bug: #1446861

heat/engine/resources/openstack/heat/resource_group.py

@@ -182,7 +182,13 @@ class ResourceGroup(stack_resource.StackResource):
         ),
     }
 
-    def validate(self):
+    def validate_nested_stack(self):
+        # Only validate the resource definition (which may be a
+        # nested template) if count is non-zero, to enable folks
+        # to disable features via a zero count if they wish
+        if not self.properties.get(self.COUNT):
+            return
+
         test_tmpl = self._assemble_nested(["0"], include_all=True)
         val_templ = template.Template(test_tmpl)
         res_def = val_templ.resource_definitions(self.stack)["0"]
@@ -193,8 +199,17 @@ class ResourceGroup(stack_resource.StackResource):
             # its a template resource
             pass
 
-        # validate the nested template definition
-        super(ResourceGroup, self).validate()
+        try:
+            name = "%s-%s" % (self.stack.name, self.name)
+            nested_stack = self._parse_nested_stack(
+                name,
+                test_tmpl,
+                self.child_params())
+            nested_stack.strict_validate = False
+            nested_stack.validate()
+        except Exception as ex:
+            msg = _("Failed to validate: %s") % six.text_type(ex)
+            raise exception.StackValidationFailed(message=msg)
 
     def _name_blacklist(self):
         """Resolve the remove_policies to names for removal."""

heat_integrationtests/functional/test_resource_group.py

@@ -109,9 +109,12 @@ resources:
                                environment=env, files=files)
         self.assertIn(expected_err, six.text_type(ex))
 
-    def _validate_resources(self, stack_identifier, expected_count):
+    def _list_group_resources(self, stack_identifier):
         nested_identifier = self._group_nested_identifier(stack_identifier)
-        resources = self.list_resources(nested_identifier)
+        return self.list_resources(nested_identifier)
+
+    def _validate_resources(self, stack_identifier, expected_count):
+        resources = self._list_group_resources(stack_identifier)
         self.assertEqual(expected_count, len(resources))
         expected_resources = dict(
             (str(idx), 'My::RandomString')
@@ -168,6 +171,44 @@ resources:
         # verify that the resource group has 3 resources
         self._validate_resources(stack_identifier, 3)
 
+    def test_update_removal_policies(self):
+        rp_template = '''
+heat_template_version: 2014-10-16
+resources:
+  random_group:
+    type: OS::Heat::ResourceGroup
+    properties:
+      count: 5
+      removal_policies: []
+      resource_def:
+        type: OS::Heat::RandomString
+'''
+
+        # create stack with resource group, initial count 5
+        stack_identifier = self.stack_create(template=rp_template)
+        self.assertEqual({u'random_group': u'OS::Heat::ResourceGroup'},
+                         self.list_resources(stack_identifier))
+        group_resources = self._list_group_resources(stack_identifier)
+        expected_resources = {u'0': u'OS::Heat::RandomString',
+                              u'1': u'OS::Heat::RandomString',
+                              u'2': u'OS::Heat::RandomString',
+                              u'3': u'OS::Heat::RandomString',
+                              u'4': u'OS::Heat::RandomString'}
+        self.assertEqual(expected_resources, group_resources)
+
+        # Remove three, specifying the middle resources to be removed
+        update_template = rp_template.replace(
+            'removal_policies: []',
+            'removal_policies: [{resource_list: [\'1\', \'2\', \'3\']}]')
+        self.update_stack(stack_identifier, update_template)
+        group_resources = self._list_group_resources(stack_identifier)
+        expected_resources = {u'0': u'OS::Heat::RandomString',
+                              u'4': u'OS::Heat::RandomString',
+                              u'5': u'OS::Heat::RandomString',
+                              u'6': u'OS::Heat::RandomString',
+                              u'7': u'OS::Heat::RandomString'}
+        self.assertEqual(expected_resources, group_resources)
+
     def test_props_update(self):
         """Test update of resource_def properties behaves as expected."""