Include file content in scenario tests

Use the heatclient utilities for loading referenced files and passing them
in the files dict when running scenario tests. This allows testing nested
stack scenarios in a way that is representative of how users would
encounter them.

Change-Id: I6693a0a9e0e1af42b69ade12c8da6f12d370eb49
Story: #1739447
Task: 22218

heat_tempest_plugin/common/test.py

@@ -10,7 +10,6 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import os
 import random
 import re
 import subprocess
@@ -206,13 +205,6 @@ class HeatIntegrationTest(testtools.testcase.WithAttributes,
             LOG.info('Console output for %s', server.id)
             LOG.info(server.get_console_output())
 
-    def _load_template(self, base_file, file_name, sub_dir=None):
-        sub_dir = sub_dir or ''
-        filepath = os.path.join(os.path.dirname(os.path.realpath(base_file)),
-                                sub_dir, file_name)
-        with open(filepath) as f:
-            return f.read()
-
     def create_keypair(self, client=None, name=None):
         if client is None:
             client = self.compute_client

heat_tempest_plugin/tests/scenario/scenario_base.py

@@ -10,6 +10,10 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import os
+import yaml
+
+from heatclient.common import template_utils
 from oslo_utils import reflection
 
 from heat_tempest_plugin.common import test
@@ -33,9 +37,19 @@ class ScenarioTestsBase(test.HeatIntegrationTest):
         if not self.conf.minimal_instance_type:
             raise self.skipException("No minimal flavor configured to test")
 
+    def _load_template(self, base_file, file_name, sub_dir=None, files=None):
+        sub_dir = sub_dir or ''
+        filepath = os.path.join(os.path.dirname(os.path.realpath(base_file)),
+                                sub_dir, file_name)
+        _files, template = template_utils.get_template_contents(filepath,
+                                                                files=files)
+        return yaml.safe_dump(template)
+
     def launch_stack(self, template_name, expected_status='CREATE_COMPLETE',
                      parameters=None, **kwargs):
-        template = self._load_template(__file__, template_name, self.sub_dir)
+        files = kwargs.get('files', {})
+        template = self._load_template(__file__, template_name, self.sub_dir,
+                                       files)
 
         parameters = parameters or {}
 
@@ -45,7 +59,7 @@ class ScenarioTestsBase(test.HeatIntegrationTest):
         stack_id = self.stack_create(
             stack_name=kwargs.get('stack_name'),
             template=template,
-            files=kwargs.get('files'),
+            files=files,
             parameters=parameters,
             environment=kwargs.get('environment'),
             expected_status=expected_status