Replace removed exceptions and prevent regression

Replaces the NoSuchMetric exception that was replaced. The exception
is replaced with MetricNotAvailable and test cases are added to prevent
regression.

The changes in the exceptions were introduced in:
https://review.opendev.org/#/c/658127/

Change-Id: Id0f872e916aaa5dec59ed1ae6c0f653553b3fe46

watcher/datasources/ceilometer.py

@@ -169,7 +169,7 @@ class CeilometerHelper(base.DataSourceBase):
 
         meter = self.METRIC_MAP.get(meter_name)
         if meter is None:
-            raise exception.NoSuchMetric()
+            raise exception.MetricNotAvailable(metric=meter_name)
 
         if aggregate == 'mean':
             aggregate = 'avg'

watcher/datasources/gnocchi.py

@@ -86,7 +86,7 @@ class GnocchiHelper(base.DataSourceBase):
 
         meter = self.METRIC_MAP.get(meter_name)
         if meter is None:
-            raise exception.NoSuchMetric()
+            raise exception.MetricNotAvailable(metric=meter_name)
 
         if aggregate == 'count':
             aggregate = 'mean'

watcher/datasources/monasca.py

@@ -97,7 +97,7 @@ class MonascaHelper(base.DataSourceBase):
 
         meter = self.METRIC_MAP.get(meter_name)
         if meter is None:
-            raise exception.NoSuchMetric()
+            raise exception.MetricNotAvailable(metric=meter_name)
 
         if aggregate == 'mean':
             aggregate = 'avg'

watcher/tests/datasources/test_ceilometer_helper.py

@@ -20,6 +20,7 @@ from __future__ import unicode_literals
 import mock
 
 from watcher.common import clients
+from watcher.common import exception
 from watcher.datasources import ceilometer as ceilometer_helper
 from watcher.tests import base
 
@@ -70,6 +71,29 @@ class TestCeilometerHelper(base.BaseTestCase):
         )
         self.assertEqual(expected_result, val)
 
+    def test_statistic_aggregation_metric_unavailable(self, mock_ceilometer):
+        helper = ceilometer_helper.CeilometerHelper()
+
+        # invalidate instance_cpu_usage in metric map
+        original_metric_value = helper.METRIC_MAP.get('instance_cpu_usage')
+        helper.METRIC_MAP.update(
+            instance_cpu_usage=None
+        )
+
+        self.assertRaises(
+            exception.MetricNotAvailable,
+            helper.statistic_aggregation, resource=mock.Mock(id="INSTANCE_ID"),
+            resource_type='instance', meter_name="instance_cpu_usage",
+            period="7300",
+            granularity=None
+        )
+
+        # restore the metric map as it is a static attribute that does not get
+        # restored between unit tests!
+        helper.METRIC_MAP.update(
+            instance_cpu_usage=original_metric_value
+        )
+
     def test_get_host_cpu_usage(self, mock_ceilometer):
         self.helper.get_host_cpu_usage('compute1', 600, 'mean')
         self.mock_aggregation.assert_called_once_with(

watcher/tests/datasources/test_gnocchi_helper.py

@@ -18,6 +18,7 @@ import mock
 from oslo_config import cfg
 
 from watcher.common import clients
+from watcher.common import exception
 from watcher.datasources import gnocchi as gnocchi_helper
 from watcher.tests import base
 
@@ -57,6 +58,28 @@ class TestGnocchiHelper(base.BaseTestCase):
         )
         self.assertEqual(expected_result, result)
 
+    def test_statistic_aggregation_metric_unavailable(self, mock_gnocchi):
+        helper = gnocchi_helper.GnocchiHelper()
+
+        # invalidate instance_cpu_usage in metric map
+        original_metric_value = helper.METRIC_MAP.get('instance_cpu_usage')
+        helper.METRIC_MAP.update(
+            instance_cpu_usage=None
+        )
+
+        self.assertRaises(
+            exception.MetricNotAvailable, helper.statistic_aggregation,
+            resource=mock.Mock(id='16a86790-327a-45f9-bc82-45839f062fdc'),
+            resource_type='instance', meter_name='instance_cpu_usage',
+            period=300, granularity=360, aggregate='mean',
+        )
+
+        # restore the metric map as it is a static attribute that does not get
+        # restored between unit tests!
+        helper.METRIC_MAP.update(
+            instance_cpu_usage=original_metric_value
+        )
+
     def test_get_host_cpu_usage(self, mock_gnocchi):
         self.helper.get_host_cpu_usage('compute1', 600, 'mean', 300)
         self.mock_aggregation.assert_called_once_with(

watcher/tests/datasources/test_monasca_helper.py

@@ -18,6 +18,7 @@ import mock
 from oslo_config import cfg
 
 from watcher.common import clients
+from watcher.common import exception
 from watcher.datasources import monasca as monasca_helper
 from watcher.tests import base
 
@@ -65,6 +66,28 @@ class TestMonascaHelper(base.BaseTestCase):
         )
         self.assertEqual(0.6, result)
 
+    def test_statistic_aggregation_metric_unavailable(self, mock_monasca):
+        helper = monasca_helper.MonascaHelper()
+
+        # invalidate host_cpu_usage in metric map
+        original_metric_value = helper.METRIC_MAP.get('host_cpu_usage')
+        helper.METRIC_MAP.update(
+            host_cpu_usage=None
+        )
+
+        self.assertRaises(
+            exception.MetricNotAvailable, helper.statistic_aggregation,
+            resource=mock.Mock(id='NODE_UUID'), resource_type='compute_node',
+            meter_name='host_cpu_usage', period=7200, granularity=300,
+            aggregate='mean',
+        )
+
+        # restore the metric map as it is a static attribute that does not get
+        # restored between unit tests!
+        helper.METRIC_MAP.update(
+            instance_cpu_usage=original_metric_value
+        )
+
     def test_check_availability(self, mock_monasca):
         monasca = mock.MagicMock()
         monasca.metrics.list.return_value = True