add content to broadcast_message and make template fields nullable

we want to be able to create broadcast messages without templates. To
start with, these will come from the API, but in future we may want to
let people create via the admin interface without creating a template
too.

populate a non-nullable content field with the values supplied via the
template (or supplied directly if via api).

tests/app/broadcast_message/test_rest.py

@@ -44,6 +44,35 @@ def test_get_broadcast_message(admin_request, sample_broadcast_service):
     assert response['personalisation'] == {'thing': 'test'}
 
 
+def test_get_broadcast_message_without_template(admin_request, sample_broadcast_service):
+    bm = create_broadcast_message(
+        service=sample_broadcast_service,
+        content='emergency broadcast content',
+        areas={
+            "areas": ['place A', 'region B'],
+            "simple_polygons": [[[50.1, 1.2], [50.12, 1.2], [50.13, 1.2]]],
+        },
+    )
+
+    response = admin_request.get(
+        'broadcast_message.get_broadcast_message',
+        service_id=sample_broadcast_service.id,
+        broadcast_message_id=bm.id,
+        _expected_status=200
+    )
+
+    assert response['id'] == str(bm.id)
+    assert response['template_id'] is None
+    assert response['template_version'] is None
+    assert response['template_name'] is None
+    assert response['content'] == 'emergency broadcast content'
+    assert response['status'] == BroadcastStatusType.DRAFT
+    assert response['created_at'] is not None
+    assert response['starts_at'] is None
+    assert response['areas'] == ['place A', 'region B']
+    assert response['personalisation'] is None
+
+
 def test_get_broadcast_message_404s_if_message_doesnt_exist(admin_request, sample_broadcast_service):
     err = admin_request.get(
         'broadcast_message.get_broadcast_message',
@@ -148,6 +177,26 @@ def test_create_broadcast_message_400s_if_json_schema_fails_validation(
     assert response['errors'] == expected_errors
 
 
+@freeze_time('2020-01-01')
+def test_create_broadcast_message_400s_if_content_provided_but_no_template(admin_request, sample_broadcast_service):
+    # we don't currently support this, but might in the future
+    response = admin_request.post(
+        'broadcast_message.create_broadcast_message',
+        _data={
+            'template_id': None,
+            'content': 'Some tailor made broadcast content',
+            'service_id': str(sample_broadcast_service.id),
+            'created_by': str(sample_broadcast_service.created_by_id),
+        },
+        service_id=sample_broadcast_service.id,
+        _expected_status=400
+    )
+    assert response['errors'] ==[
+        {'error': 'ValidationError', 'message': 'template_id is not a valid UUID'},
+        {'error': 'ValidationError', 'message': 'Additional properties are not allowed (content was unexpected)'},
+    ]
+
+
 @pytest.mark.parametrize('status', [
     BroadcastStatusType.DRAFT,
     BroadcastStatusType.PENDING_APPROVAL,
@@ -394,6 +443,40 @@ def test_update_broadcast_message_status_stores_approved_by_and_approved_at_and_
     assert alert_event.transmitted_content == {"body": "emergency broadcast"}
 
 
+def test_update_broadcast_message_status_creates_event_with_correct_content_if_broadcast_has_no_template(
+    admin_request,
+    sample_broadcast_service,
+    mocker
+):
+    bm = create_broadcast_message(
+        service=sample_broadcast_service,
+        template=None,
+        content='tailor made emergency broadcast content',
+        status=BroadcastStatusType.PENDING_APPROVAL,
+        areas={"areas": ["london"], "simple_polygons": [[[51.30, 0.7], [51.28, 0.8], [51.25, -0.7]]]}
+    )
+    approver = create_user(email='approver@gov.uk')
+    sample_broadcast_service.users.append(approver)
+    mock_task = mocker.patch('app.celery.broadcast_message_tasks.send_broadcast_event.apply_async')
+
+    response = admin_request.post(
+        'broadcast_message.update_broadcast_message_status',
+        _data={'status': BroadcastStatusType.BROADCASTING, 'created_by': str(approver.id)},
+        service_id=sample_broadcast_service.id,
+        broadcast_message_id=bm.id,
+        _expected_status=200
+    )
+
+    assert response['status'] == BroadcastStatusType.BROADCASTING
+
+    assert len(bm.events) == 1
+    alert_event = bm.events[0]
+
+    mock_task.assert_called_once_with(kwargs={'broadcast_event_id': str(alert_event.id)}, queue='notify-internal-tasks')
+
+    assert alert_event.transmitted_content == {"body": "tailor made emergency broadcast content"}
+
+
 def test_update_broadcast_message_status_rejects_approval_from_creator(
     admin_request,
     sample_broadcast_service,