Add OS::Heat::None resource

Adds a new resource, designed to enable easy "stubbing out"
of resources via the environment resource_registry.

It takes any properties, and returns any attribute (as None),
meaning it can be uses in place of "noop" nested stacks which
dummy an existing resources by matching parameters/outputs to
properties/attributes.

Implements: blueprint noop-resource
Change-Id: Idc485a9fcf7287030dda22f893486279be9e1a68

heat/engine/resources/openstack/heat/none_resource.py

@@ -0,0 +1,56 @@
+#
+#    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.
+
+import six
+import uuid
+
+from heat.engine import properties
+from heat.engine import resource
+from heat.engine import support
+
+
+class NoneResource(resource.Resource):
+    '''
+    A resource which enables easily disabling certain resources via the
+    resource_registry.  It does nothing, but can effectively stub out
+    any other resource because it will accept any properties and return
+    any attribute (as None).  Note this resource always does nothing
+    on update (e.g it is not replaced even if a change to the stubbed
+    resource properties would cause replacement).
+    '''
+
+    support_status = support.SupportStatus(version='5.0.0')
+    properties_schema = {}
+    attributes_schema = {}
+
+    def _needs_update(self, after, before, after_props, before_props,
+                      prev_resource):
+        return False
+
+    def reparse(self):
+        self.properties = properties.Properties(schema={}, data={})
+
+    def handle_create(self):
+        self.resource_id_set(six.text_type(uuid.uuid4()))
+
+    def validate(self):
+        pass
+
+    def FnGetAtt(self, key, *path):
+        return None
+
+
+def resource_mapping():
+    return {
+        'OS::Heat::None': NoneResource,
+    }

heat/tests/test_none_resource.py

@@ -0,0 +1,77 @@
+#
+#    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.
+
+from heat.common import template_format
+from heat.tests import common
+from heat.tests import utils
+
+
+class NoneResourceTest(common.HeatTestCase):
+
+    tmpl = '''
+heat_template_version: 2015-10-15
+resources:
+  none:
+    type: OS::Heat::None
+    properties:
+      ignored: foo
+outputs:
+  anything:
+    value: {get_attr: [none, anything]}
+'''
+
+    def _create_none_stack(self):
+        self.t = template_format.parse(self.tmpl)
+        self.stack = utils.parse_stack(self.t)
+        self.rsrc = self.stack['none']
+        self.assertIsNone(self.rsrc.validate())
+        self.stack.create()
+        self.assertEqual(self.rsrc.CREATE, self.rsrc.action)
+        self.assertEqual(self.rsrc.COMPLETE, self.rsrc.status)
+        self.assertEqual(self.stack.CREATE, self.stack.action)
+        self.assertEqual(self.stack.COMPLETE, self.stack.status)
+        self.assertEqual(None, self.stack.output('anything'))
+
+    def test_none_stack_create(self):
+        self._create_none_stack()
+
+    def test_none_stack_update_nochange(self):
+        self._create_none_stack()
+        before_refid = self.rsrc.FnGetRefId()
+        self.assertIsNotNone(before_refid)
+        utils.update_stack(self.stack, self.t)
+        self.assertEqual((self.stack.UPDATE, self.stack.COMPLETE),
+                         self.stack.state)
+        self.assertEqual(before_refid, self.stack['none'].FnGetRefId())
+
+    def test_none_stack_update_add_prop(self):
+        self._create_none_stack()
+        before_refid = self.rsrc.FnGetRefId()
+        self.assertIsNotNone(before_refid)
+        new_t = self.t.copy()
+        new_t['resources']['none']['properties']['another'] = 123
+        utils.update_stack(self.stack, new_t)
+        self.assertEqual((self.stack.UPDATE, self.stack.COMPLETE),
+                         self.stack.state)
+        self.assertEqual(before_refid, self.stack['none'].FnGetRefId())
+
+    def test_none_stack_update_del_prop(self):
+        self._create_none_stack()
+        before_refid = self.rsrc.FnGetRefId()
+        self.assertIsNotNone(before_refid)
+        new_t = self.t.copy()
+        del(new_t['resources']['none']['properties']['ignored'])
+        utils.update_stack(self.stack, new_t)
+        self.assertEqual((self.stack.UPDATE, self.stack.COMPLETE),
+                         self.stack.state)
+        self.assertEqual(before_refid, self.stack['none'].FnGetRefId())

heat/tests/utils.py

@@ -102,6 +102,15 @@ def parse_stack(t, params=None, files=None, stack_name=None,
     return stk
 
 
+def update_stack(stk, new_t, params=None, files=None):
+    ctx = dummy_context()
+    templ = template.Template(new_t, files=files,
+                              env=environment.Environment(params))
+    updated_stack = stack.Stack(ctx, 'updated_stack', templ)
+
+    stk.update(updated_stack)
+
+
 class PhysName(object):
 
     mock_short_id = 'x' * 12