fix enroll and reenroll relationship

enrollments-events/tests/events/test_enroll.py

@@ -1,6 +1,6 @@
 import app.events.enroll as app
 from aws_lambda_powertools.utilities.typing import LambdaContext
-from layercake.dynamodb import DynamoDBPersistenceLayer
+from layercake.dynamodb import DynamoDBPersistenceLayer, KeyPair
 
 
 def test_enroll(
@@ -8,12 +8,26 @@ def test_enroll(
     dynamodb_persistence_layer: DynamoDBPersistenceLayer,
     lambda_context: LambdaContext,
 ):
+    order_id = 'cpYSbBcie2NDbZhDKCxCih'
     event = {
         'detail': {
             'new_image': {
-                'id': 'cpYSbBcie2NDbZhDKCxCih',
+                'id': order_id,
                 'sk': 'generated_items',
             }
         }
     }
     assert app.lambda_handler(event, lambda_context)  # type: ignore
+
+    # Parent knows the child
+    order_entity = dynamodb_persistence_layer.collection.get_item(
+        KeyPair(order_id, 'LINKED_ENTITIES#ORDER#CHILD')
+    )
+    assert order_entity
+
+    # Child knows the parent
+    enrollment_entity = dynamodb_persistence_layer.collection.get_item(
+        KeyPair(order_entity['enrollment_id'], 'LINKED_ENTITIES#ORDER#PARENT'),
+    )
+
+    assert enrollment_entity['order_id'] == order_id