diff --git a/scripts/test_s3.py b/test_scripts/test_scripts_for_s3.py
similarity index 97%
rename from scripts/test_s3.py
rename to test_scripts/test_scripts_for_s3.py
index 3809cba24..4510c4e6d 100644
--- a/scripts/test_s3.py
+++ b/test_scripts/test_scripts_for_s3.py
@@ -42,7 +42,7 @@ def test_get_file_content():
             print(content)
 
 
-def test_letter_ack_file_strip_correctly():
+def test_letter_ack_file_parse_content_correctly():
     # Test ack files are stripped correctly. In the acknowledgement file, there should be 2 zip files,
     # 'NOTIFY.20180111175007.ZIP','NOTIFY.20180111175008.ZIP'.
     zip_file_list = ['NOTIFY.20180111175007.ZIP', 'NOTIFY.20180111175008.ZIP', 'NOTIFY.20180111175009.ZIP']
diff --git a/tests/app/celery/test_scheduled_tasks.py b/tests/app/celery/test_scheduled_tasks.py
index 5054afd82..2dfef2623 100644
--- a/tests/app/celery/test_scheduled_tasks.py
+++ b/tests/app/celery/test_scheduled_tasks.py
@@ -1039,9 +1039,9 @@ def mock_s3_get_list_match(bucket_name, subfolder='', suffix=''):
 
 
 def mock_s3_get_list_diff(bucket_name, subfolder='', suffix=''):
-
     if subfolder == '2018-01-11':
-        return ['NOTIFY.20180111175007.ZIP', 'NOTIFY.20180111175008.ZIP', 'NOTIFY.20180111175009.ZIP']
+        return ['NOTIFY.20180111175007.ZIP', 'NOTIFY.20180111175008.ZIP', 'NOTIFY.20180111175009.ZIP',
+                'NOTIFY.20180111175010.ZIP']
     print(suffix)
     if subfolder == 'root/dispatch':
         return ['root/dispatch/NOTIFY.20180111175733.ACK.txt']
@@ -1069,6 +1069,6 @@ def test_letter_not_raise_alert_if_ack_files_not_match_zip_list(mocker, notify_d
     with pytest.raises(expected_exception=NoAckFileReceived) as e:
         letter_raise_alert_if_no_ack_file_for_zip()
 
-    assert e.value.message == ['NOTIFY.20180111175009.ZIP']
+    assert e.value.message == ['NOTIFY.20180111175009.ZIP', 'NOTIFY.20180111175010.ZIP']
     assert mock_file_list.call_count == 2
     assert mock_get_file.call_count == 1
diff --git a/tests/app/notifications/rest/test_callbacks.py b/tests/app/notifications/rest/test_callbacks.py
index af51f7719..e81a91042 100644
--- a/tests/app/notifications/rest/test_callbacks.py
+++ b/tests/app/notifications/rest/test_callbacks.py
@@ -80,12 +80,14 @@ def test_dvla_callback_calls_update_letter_notifications_task(client, mocker):
     update_task.assert_called_with(['bar.rs.txt'], queue='notify-internal-tasks')
 
 
-def test_dvla_callback_does_not_raise_error_parsing_json_for_plaintext_header(client, mocker):
-    mocker.patch('app.notifications.notifications_letter_callback.update_letter_notifications_statuses.apply_async')
-    data = _sample_sns_s3_callback()
+def test_dvla_ack_calls_does_not_call_letter_notifications_task(client, mocker):
+    update_task = \
+        mocker.patch('app.notifications.notifications_letter_callback.update_letter_notifications_statuses.apply_async')
+    data = _sample_sns_s3_dvla_ack()
     response = dvla_post(client, data)
 
     assert response.status_code == 200
+    update_task.assert_not_called()
 
 
 def test_firetext_callback_should_not_need_auth(client, mocker):
@@ -460,7 +462,7 @@ def test_firetext_callback_should_record_statsd(client, notify_db, notify_db_ses
         app.statsd_client.incr.assert_any_call("callback.firetext.delivered")
 
 
-def _sample_sns_s3_callback():
+def _sample_sns_s3_dvla_ack():
     return json.dumps({
         "SigningCertURL": "foo.pem",
         "UnsubscribeURL": "bar",
@@ -471,7 +473,7 @@ def _sample_sns_s3_callback():
         "MessageId": "6adbfe0a-d610-509a-9c47-af894e90d32d",
         "Subject": "Amazon S3 Notification",
         "TopicArn": "sample-topic-arn",
-        "Message": '{"Records":[{"eventVersion":"2.0","eventSource":"aws:s3","awsRegion":"eu-west-1","eventTime":"2017-05-16T11:38:41.073Z","eventName":"ObjectCreated:Put","userIdentity":{"principalId":"some-p-id"},"requestParameters":{"sourceIPAddress":"8.8.8.8"},"responseElements":{"x-amz-request-id":"some-r-id","x-amz-id-2":"some-x-am-id"},"s3":{"s3SchemaVersion":"1.0","configurationId":"some-c-id","bucket":{"name":"some-bucket","ownerIdentity":{"principalId":"some-p-id"},"arn":"some-bucket-arn"},"object":{"key":"bar.txt","size":200,"eTag":"some-e-tag","versionId":"some-v-id","sequencer":"some-seq"}}}]}'  # noqa
+        "Message": '{"Records":[{"eventVersion":"2.0","eventSource":"aws:s3","awsRegion":"eu-west-1","eventTime":"2017-05-16T11:38:41.073Z","eventName":"ObjectCreated:Put","userIdentity":{"principalId":"some-p-id"},"requestParameters":{"sourceIPAddress":"8.8.8.8"},"responseElements":{"x-amz-request-id":"some-r-id","x-amz-id-2":"some-x-am-id"},"s3":{"s3SchemaVersion":"1.0","configurationId":"some-c-id","bucket":{"name":"some-bucket","ownerIdentity":{"principalId":"some-p-id"},"arn":"some-bucket-arn"},"object":{"key":"bar.ack.txt","size":200,"eTag":"some-e-tag","versionId":"some-v-id","sequencer":"some-seq"}}}]}'  # noqa
     })