VED-842: Exception Handlers (#1094)

Author: JamesW1-NHS

lambdas/delta_backend/src/delta.py

@@ -232,7 +232,6 @@ def handler(event, _context):
             "diagnostics": "Delta Lambda failure: Incorrect invocation of Lambda",
         }
         logger.exception(operation_outcome["diagnostics"])
-        send_message(event)  # Send failed records to DLQ
         log_data = {"function_name": "delta_sync", "operation_outcome": operation_outcome}
         send_log_to_firehose(STREAM_NAME, log_data)
 

lambdas/delta_backend/tests/test_delta.py

@@ -2,7 +2,7 @@
 import json
 import os
 import unittest
-from unittest.mock import MagicMock, patch
+from unittest.mock import MagicMock, call, patch
 
 from botocore.exceptions import ClientError
 
@@ -114,6 +114,25 @@ def test_handler_success_insert(self):
             self.assertEqual(put_item_data["SupplierSystem"], supplier)
             self.mock_sqs_client.send_message.assert_not_called()
 
+    def test_handler_exception(self):
+        """Ensure that sqs_client exceptions do not cause the lambda handler itself to raise an exception"""
+
+        # Arrange
+        self.mock_sqs_client.send_message.side_effect = Exception("SQS error")
+        event = {"invalid_format": True}
+
+        # Act
+        result = handler(event, None)
+
+        # Assert
+        self.assertFalse(result)
+        self.mock_logger_exception.assert_has_calls(
+            [
+                call("Delta Lambda failure: Incorrect invocation of Lambda"),
+                call("Error sending record to DLQ"),
+            ]
+        )
+
     def test_handler_overall_failure(self):
         # Arrange
         event = {"invalid_format": True}

lambdas/recordforwarder/tests/test_forwarding_batch_lambda.py

@@ -863,20 +863,48 @@ def test_forward_request_to_dynamo(
         expected_values = test_case[0]["expected_values"]
         assert expected_values.items() <= call_data.items()
 
-    def clear_test_tables(self):
-        """Clear DynamoDB table after each test."""
-        scan = self.table.scan()
-        items = scan.get("Items", [])
-        while items:
-            for item in items:
-                self.table.delete_item(Key={"PK": item["PK"]})
-            scan = self.table.scan()
-            items = scan.get("Items", [])
-
-    def teardown(self):
-        """Deletes mock dynamodb resource"""
-        self.table.delete()
-        self.dynamodb_resource = None
+    @patch("forwarding_batch_lambda.sqs_client.send_message")
+    def test_forward_lambda_handler_exception_handler(self, mock_send_message):
+        """Test exception handling when sqs_client fails"""
+        # Arrange
+        # Ensure there is at least one failure, so that sqs_client is called
+        test_cases = [
+            {
+                "name": "Row 1: Duplication Error: Create failure ",
+                "input": self.generate_input(row_id=1, operation_requested="CREATE", include_fhir_json=True),
+                "expected_keys": ForwarderValues.EXPECTED_KEYS_DIAGNOSTICS,
+                "expected_values": {
+                    "row_id": "row-1",
+                    "diagnostics": create_diagnostics_dictionary(
+                        IdentifierDuplicationError("https://www.ravs.england.nhs.uk/#RSV_002")
+                    ),
+                },
+                "is_failure": True,
+            },
+        ]
+
+        self.table.put_item(
+            Item={
+                "PK": "Immunization#4d2ac1eb-080f-4e54-9598-f2d53334681c",
+                "PatientPK": "Patient#9732928395",
+                "PatientSK": "RSV#4d2ac1eb-080f-4e54-9598-f2d53334681c",
+                "IdentifierPK": "https://www.ravs.england.nhs.uk/#RSV_002",
+                "Version": 1,
+            }
+        )
+
+        mock_send_message.side_effect = Exception("Unknown Exception in SQS client")
+
+        event = self.generate_event(test_cases)
+
+        self.mock_redis.hget.return_value = "RSV"
+        self.mock_redis_getter.return_value = self.mock_redis
+
+        # Act & Assert
+        with self.assertRaises(Exception) as context:
+            forward_lambda_handler(event, {})
+
+        self.assertEqual("Unknown Exception in SQS client", str(context.exception))
 
 
 if __name__ == "__main__":