fix: remove DeleteMessageBatch call to SQS api if there are no messages to delete (#170)

Author: Tom McCarthy

aws_lambda_powertools/utilities/batch/sqs.py

@@ -115,7 +115,9 @@ def _clean(self):
         queue_url = self._get_queue_url()
         entries_to_remove = self._get_entries_to_clean()
 
-        delete_message_response = self.client.delete_message_batch(QueueUrl=queue_url, Entries=entries_to_remove)
+        delete_message_response = None
+        if entries_to_remove:
+            delete_message_response = self.client.delete_message_batch(QueueUrl=queue_url, Entries=entries_to_remove)
 
         if self.suppress_exception:
             logger.debug(f"{len(self.fail_messages)} records failed processing, but exceptions are suppressed")

tests/functional/test_utilities_batch.py

@@ -275,3 +275,18 @@ def lambda_handler(event, context):
 
     stubber.assert_no_pending_responses()
     assert result is True
+
+
+def test_partial_sqs_processor_context_only_failure(sqs_event_factory, record_handler, partial_processor):
+    """
+    Test processor with only failures
+    """
+    first_record = sqs_event_factory("fail")
+    second_record = sqs_event_factory("fail")
+
+    records = [first_record, second_record]
+    with pytest.raises(SQSBatchProcessingError) as error:
+        with partial_processor(records, record_handler) as ctx:
+            ctx.process()
+
+    assert len(error.value.args[0]) == 2