Added missing test on GMR plugin

The show_models() function was not covered by any test so this
changeset is adding a new unit test for it.

Change-Id: Ia861f049c1f1ee0aa623404e62fb002392c9052d

watcher/tests/decision_engine/test_gmr.py

@@ -0,0 +1,36 @@
+# -*- encoding: utf-8 -*-
+# Copyright (c) 2016 b<>com
+#
+# Authors: Vincent FRANCOISE <vincent.francoise@b-com.com>
+#
+# 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 mock
+
+from watcher.decision_engine import gmr
+from watcher.decision_engine.model.collector import manager
+from watcher.tests import base
+
+
+class TestGmrPlugin(base.TestCase):
+
+    @mock.patch.object(manager.CollectorManager, "get_collectors")
+    def test_show_models(self, m_get_collectors):
+        m_to_string = mock.Mock(return_value="<TESTMODEL />")
+        m_get_collectors.return_value = {
+            "test_model": mock.Mock(
+                cluster_data_model=mock.Mock(to_string=m_to_string))}
+        output = gmr.show_models()
+        self.assertEqual(1, m_to_string.call_count)
+        self.assertIn("<TESTMODEL />", output)