orchestration API add coverage for stack update API

Currently we have no coverage of the stack update API, although there
is a function for it in orchestration_client.  So add a simple test of
the stack update API surface.

Change-Id: I46dba8e4d7d5c4e30d341b6269897386ce9bf378
diff --git a/tempest/api/orchestration/stacks/test_update.py b/tempest/api/orchestration/stacks/test_update.py
new file mode 100644
index 0000000..1bda0b4
--- /dev/null
+++ b/tempest/api/orchestration/stacks/test_update.py
@@ -0,0 +1,83 @@
+#    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 logging
+
+from tempest.api.orchestration import base
+from tempest.common.utils import data_utils
+from tempest.test import attr
+
+
+LOG = logging.getLogger(__name__)
+
+
+class UpdateStackTestJSON(base.BaseOrchestrationTest):
+    _interface = 'json'
+
+    template = '''
+heat_template_version: 2013-05-23
+resources:
+  random1:
+    type: OS::Heat::RandomString
+'''
+    update_template = '''
+heat_template_version: 2013-05-23
+resources:
+  random1:
+    type: OS::Heat::RandomString
+  random2:
+    type: OS::Heat::RandomString
+'''
+
+    def update_stack(self, stack_identifier, template):
+        stack_name = stack_identifier.split('/')[0]
+        resp = self.client.update_stack(
+            stack_identifier=stack_identifier,
+            name=stack_name,
+            template=template)
+        self.assertEqual('202', resp[0]['status'])
+        self.client.wait_for_stack_status(stack_identifier, 'UPDATE_COMPLETE')
+
+    @attr(type='gate')
+    def test_stack_update_nochange(self):
+        stack_name = data_utils.rand_name('heat')
+        stack_identifier = self.create_stack(stack_name, self.template)
+        self.client.wait_for_stack_status(stack_identifier, 'CREATE_COMPLETE')
+        expected_resources = {'random1': 'OS::Heat::RandomString'}
+        self.assertEqual(expected_resources,
+                         self.list_resources(stack_identifier))
+
+        # Update with no changes, resources should be unchanged
+        self.update_stack(stack_identifier, self.template)
+        self.assertEqual(expected_resources,
+                         self.list_resources(stack_identifier))
+
+    @attr(type='gate')
+    def test_stack_update_add_remove(self):
+        stack_name = data_utils.rand_name('heat')
+        stack_identifier = self.create_stack(stack_name, self.template)
+        self.client.wait_for_stack_status(stack_identifier, 'CREATE_COMPLETE')
+        initial_resources = {'random1': 'OS::Heat::RandomString'}
+        self.assertEqual(initial_resources,
+                         self.list_resources(stack_identifier))
+
+        # Add one resource via a stack update
+        self.update_stack(stack_identifier, self.update_template)
+        updated_resources = {'random1': 'OS::Heat::RandomString',
+                             'random2': 'OS::Heat::RandomString'}
+        self.assertEqual(updated_resources,
+                         self.list_resources(stack_identifier))
+
+        # Then remove it by updating with the original template
+        self.update_stack(stack_identifier, self.template)
+        self.assertEqual(initial_resources,
+                         self.list_resources(stack_identifier))