Implements base method for time series metrics

Implements base method as well as some basic implementations to
retrieve time series metrics. Ceilometer can not be supported
as API documentation has been unavailable. Grafana will be
supported in follow-up patch.

Partially Implements: blueprint time-series-framework

Change-Id: I55414093324c8cff379b28f5b855f41a9265c2d3

watcher/tests/decision_engine/datasources/test_monasca_helper.py

@@ -13,7 +13,7 @@
 # implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
+from datetime import datetime
 from unittest import mock
 
 from oslo_config import cfg
@@ -67,6 +67,43 @@ class TestMonascaHelper(base.BaseTestCase):
         )
         self.assertEqual(0.6, result)
 
+    def test_monasca_statistic_series(self, mock_monasca):
+        monasca = mock.MagicMock()
+        expected_stat = [{
+            'columns': ['timestamp', 'avg'],
+            'dimensions': {
+                'hostname': 'rdev-indeedsrv001',
+                'service': 'monasca'},
+            'id': '0',
+            'name': 'cpu.percent',
+            'statistics': [
+                ['2016-07-29T12:45:00Z', 0.0],
+                ['2016-07-29T12:50:00Z', 0.9],
+                ['2016-07-29T12:55:00Z', 0.9]]}]
+
+        expected_result = {
+            '2016-07-29T12:45:00Z': 0.0,
+            '2016-07-29T12:50:00Z': 0.9,
+            '2016-07-29T12:55:00Z': 0.9,
+        }
+
+        monasca.metrics.list_statistics.return_value = expected_stat
+        mock_monasca.return_value = monasca
+
+        start = datetime(year=2016, month=7, day=29, hour=12, minute=45)
+        end = datetime(year=2016, month=7, day=29, hour=12, minute=55)
+
+        helper = monasca_helper.MonascaHelper()
+        result = helper.statistic_series(
+            resource=mock.Mock(id='NODE_UUID'),
+            resource_type='compute_node',
+            meter_name='host_cpu_usage',
+            start_time=start,
+            end_time=end,
+            granularity=300,
+        )
+        self.assertEqual(expected_result, result)
+
     def test_statistic_aggregation_metric_unavailable(self, mock_monasca):
         helper = monasca_helper.MonascaHelper()