Fixes duplicated names in alarm time constraints

Currently, an alarm can have multiple time constraints
with the same name. Consequently the constraints aren't
uniquely identifiable and cannot be edited correctly.

This patch adds duplicate checking.

Change-Id: I6654e13b249db53c2107b43fe36ddacedf67be67
Closes-bug: #1293994

ceilometer/api/controllers/v2.py

@@ -1737,6 +1737,12 @@ class Alarm(_Base):
                 if not alarms:
                     raise EntityNotFound(_('Alarm'), id)
 
+        tc_names = [tc.name for tc in alarm.time_constraints]
+        if len(tc_names) > len(set(tc_names)):
+            error = _("Time constraint names must be "
+                      "unique for a given alarm.")
+            raise ClientSideError(error)
+
         return alarm
 
     @classmethod

ceilometer/tests/api/v2/test_alarm_scenarios.py

@@ -338,6 +338,35 @@ class TestAlarms(FunctionalTest,
         alarms = list(self.conn.get_alarms())
         self.assertEqual(4, len(alarms))
 
+    def test_post_duplicate_time_constraint_name(self):
+        json = {
+            'name': 'added_alarm_duplicate_constraint_name',
+            'type': 'threshold',
+            'time_constraints': [
+                {
+                    'name': 'testcons',
+                    'start': '* 11 * * *',
+                    'duration': 10
+                },
+                {
+                    'name': 'testcons',
+                    'start': '* * * * *',
+                    'duration': 20
+                }
+            ],
+            'threshold_rule': {
+                'meter_name': 'ameter',
+                'threshold': 300.0
+            }
+        }
+        resp = self.post_json('/alarms', params=json, expect_errors=True,
+                              status=400, headers=self.auth_headers)
+        self.assertEqual(
+            "Time constraint names must be unique for a given alarm.",
+            resp.json['error_message']['faultstring'])
+        alarms = list(self.conn.get_alarms())
+        self.assertEqual(4, len(alarms))
+
     def test_post_invalid_alarm_time_constraint_duration(self):
         json = {
             'name': 'added_alarm_invalid_constraint_duration',