Refactor code

- Created TaskNames for DVLA_FILES rather than have DVLA_FILES in QueueNames
- Removed PROCESS_FTP from all_queues() as this was causing problems in picking up letter job tasks
- Created test to ensure that we don't arbitrarily add queue names to all_queues

tests/app/test_config.py

@@ -5,6 +5,7 @@ from unittest import mock
 import pytest
 
 from app import config
+from app.config import QueueNames
 
 
 def cf_conf():
@@ -57,3 +58,20 @@ def test_load_config_if_cloudfoundry_not_available(monkeypatch, reload_config):
 def test_cloudfoundry_config_has_different_defaults():
     # these should always be set on Sandbox
     assert config.Sandbox.REDIS_ENABLED is False
+
+
+def test_queue_names_all_queues_correct():
+    # Need to ensure that all_queues() only returns queue names used in API
+    queues = QueueNames.all_queues()
+    assert len(queues) == 10
+    assert set([QueueNames.PRIORITY,
+                QueueNames.PERIODIC,
+                QueueNames.DATABASE,
+                QueueNames.SEND_SMS,
+                QueueNames.SEND_EMAIL,
+                QueueNames.RESEARCH_MODE,
+                QueueNames.STATISTICS,
+                QueueNames.JOBS,
+                QueueNames.RETRY,
+                QueueNames.NOTIFY
+                ]) == set(queues)