Added tests to validate that the API contract is maintained by comparing actual vs mock API responses

tests/test_todos.py

@@ -67,3 +67,22 @@ def testing_getting_uncompleted_todos_when_todos_is_none():
         uncompleted_todos = get_uncompleted_todos()
         assert mock_get_todos.called
         assert uncompleted_todos == []
+
+
+def test_integration_contract():
+    actual = get_todos()
+    actual_keys = actual.json().pop().keys()
+
+    with patch('apitesting.services.requests.get') as mock_get:
+        mock_get.return_value.ok = True
+        mock_get.return_value.json.return_value = [{
+            'userId': 1,
+            'id': 1,
+            'title': 'Make the bed',
+            'completed': False
+        }]
+
+        mocked = get_todos()
+        mocked_keys = mocked.json().pop().keys()
+
+    assert set(actual_keys) == set(mocked_keys)