add tests for get_earlier_events_for_broadcast_event

tests/app/dao/test_broadcast_message_dao.py

@@ -0,0 +1,43 @@
+from datetime import datetime
+from app.models import BROADCAST_TYPE
+from app.models import BroadcastEventMessageType
+from app.dao.broadcast_message_dao import get_earlier_events_for_broadcast_event
+
+from tests.app.db import create_broadcast_message, create_template, create_broadcast_event
+
+
+def test_get_earlier_events_for_broadcast_event(sample_service):
+    t = create_template(sample_service, BROADCAST_TYPE)
+    bm = create_broadcast_message(t)
+
+    events = [
+        create_broadcast_event(
+            bm,
+            sent_at=datetime(2020, 1, 1, 12, 0, 0),
+            message_type=BroadcastEventMessageType.ALERT,
+            transmitted_content={'body': 'Initial content'}
+        ),
+        create_broadcast_event(
+            bm,
+            sent_at=datetime(2020, 1, 1, 13, 0, 0),
+            message_type=BroadcastEventMessageType.UPDATE,
+            transmitted_content={'body': 'Updated content'}
+        ),
+        create_broadcast_event(
+            bm,
+            sent_at=datetime(2020, 1, 1, 14, 0, 0),
+            message_type=BroadcastEventMessageType.UPDATE,
+            transmitted_content={'body': 'Updated content'},
+            transmitted_areas=['wales']
+        ),
+        create_broadcast_event(
+            bm,
+            sent_at=datetime(2020, 1, 1, 15, 0, 0),
+            message_type=BroadcastEventMessageType.CANCEL,
+            transmitted_finishes_at=datetime(2020, 1, 1, 15, 0, 0),
+        )
+    ]
+
+    # only fetches earlier events, and they're in time order
+    earlier_events = get_earlier_events_for_broadcast_event(events[2].id)
+    assert earlier_events == [events[0], events[1]]