diff --git a/server/src/test/return_all_data/test_return_all_data.py b/server/src/test/return_all_data/test_return_all_data.py
new file mode 100644
index 0000000..509eb41
--- /dev/null
+++ b/server/src/test/return_all_data/test_return_all_data.py
@@ -0,0 +1,127 @@
+import unittest
+from unittest.mock import patch, MagicMock
+import json
+import os
+from functions.return_all_data.lambda_function import lambda_handler
+
+
+class TestLambdaFunction(unittest.TestCase):
+
+    # Mock environment variable before each test
+    def setUp(self):
+        patch.dict(os.environ, {'TABLE_NAME': 'test-table'}).start()
+
+    # Clean up patches after each test
+    def tearDown(self):
+        patch.stopall()
+
+    @patch('functions.return_all_data.lambda_function.dynamodb.Table')
+    def test_lambda_handler_with_object_type(self, mock_table):
+        # Mock scan response for specific object types
+        mock_table.return_value.scan.return_value = {
+            'Items': [
+                {'objectID': '1', 'objectType': 'Bus'},
+                {'objectID': '2', 'objectType': 'Train'}
+            ]
+        }
+
+        # Mock event with objectType query parameter
+        event = {
+            'queryStringParameters': {
+                'objectType': 'Bus,Train'
+            }
+        }
+
+        result = lambda_handler(event, {})
+        self.assertEqual(result['statusCode'], 200)
+
+        # Parse result body
+        body = json.loads(result['body'])
+        self.assertEqual(len(body), 2)
+        self.assertEqual(body[0]['objectType'], 'Bus')
+        self.assertEqual(body[1]['objectType'], 'Train')
+
+    @patch('functions.return_all_data.lambda_function.dynamodb.Table')
+    def test_lambda_handler_with_pagination(self, mock_table):
+        # Mock paginated scan responses
+        mock_table.return_value.scan.side_effect = [
+            {'Items': [{'objectID': '1', 'objectType': 'Bus'}], 'LastEvaluatedKey': 'key1'},
+            {'Items': [{'objectID': '2', 'objectType': 'Train'}], 'LastEvaluatedKey': 'key2'},
+            {'Items': [{'objectID': '3', 'objectType': 'Luas'}]}
+        ]
+
+        event = {
+            'queryStringParameters': {
+                'objectType': 'Bus,Train,Luas'
+            }
+        }
+
+        result = lambda_handler(event, {})
+        self.assertEqual(result['statusCode'], 200)
+
+        body = json.loads(result['body'])
+        self.assertEqual(len(body), 3)
+        self.assertEqual(body[0]['objectType'], 'Bus')
+        self.assertEqual(body[1]['objectType'], 'Train')
+        self.assertEqual(body[2]['objectType'], 'Luas')
+
+    @patch('functions.return_all_data.lambda_function.dynamodb.Table')
+    def test_lambda_handler_without_object_type(self, mock_table):
+        # Mock scan response for full table scan
+        mock_table.return_value.scan.return_value = {
+            'Items': [
+                {'objectID': '1', 'objectType': 'Bus'},
+                {'objectID': '2', 'objectType': 'Train'}
+            ]
+        }
+
+        # Mock event without objectType query parameter
+        event = {
+            'queryStringParameters': None
+        }
+
+        result = lambda_handler(event, {})
+        self.assertEqual(result['statusCode'], 200)
+
+        body = json.loads(result['body'])
+        self.assertEqual(len(body), 2)
+        self.assertEqual(body[0]['objectType'], 'Bus')
+        self.assertEqual(body[1]['objectType'], 'Train')
+
+    @patch('functions.return_all_data.lambda_function.dynamodb.Table')
+    def test_lambda_handler_with_no_items(self, mock_table):
+        # Mock empty scan response
+        mock_table.return_value.scan.return_value = {
+            'Items': []
+        }
+
+        # Mock event without objectType query parameter
+        event = {
+            'queryStringParameters': None
+        }
+
+        result = lambda_handler(event, {})
+        self.assertEqual(result['statusCode'], 200)
+
+        body = json.loads(result['body'])
+        self.assertEqual(len(body), 0)
+
+    @patch('functions.return_all_data.lambda_function.dynamodb.Table')
+    def test_lambda_handler_error(self, mock_table):
+        # Mock table scan to raise an exception
+        mock_table.return_value.scan.side_effect = Exception('DynamoDB error')
+
+        event = {
+            'queryStringParameters': None
+        }
+
+        result = lambda_handler(event, {})
+        self.assertEqual(result['statusCode'], 500)
+
+        body = json.loads(result['body'])
+        self.assertIn('error', body)
+        self.assertEqual(body['error'], 'DynamoDB error')
+
+
+if __name__ == "__main__":
+    unittest.main()