Fix some review related code snippets

arkindex_worker/cache.py

@@ -6,7 +6,7 @@ from arkindex_worker import logger
 
 SQL_ELEMENTS_TABLE_CREATION = """CREATE TABLE IF NOT EXISTS elements (
     id VARCHAR(32) PRIMARY KEY,
-    parent_id VARCHAR(32) NOT NULL,
+    parent_id VARCHAR(32),
     name TEXT NOT NULL,
     type TEXT NOT NULL,
     polygon TEXT,
@@ -17,8 +17,8 @@ SQL_ELEMENTS_TABLE_CREATION = """CREATE TABLE IF NOT EXISTS elements (
 
 CachedElement = namedtuple(
     "CachedElement",
-    ["id", "parent_id", "name", "type", "polygon", "worker_version_id", "initial"],
-    defaults=[0],
+    ["id", "name", "type", "polygon", "worker_version_id", "parent_id", "initial"],
+    defaults=[None, 0],
 )
 
 

tests/test_cache.py

@@ -60,7 +60,7 @@ def test_create_tables_existing_table():
     with open(db_path, "rb") as after_file:
         after = after_file.read()
 
-    assert before == after
+    assert before == after, "Cache was modified"
 
 
 def test_create_tables():
@@ -113,7 +113,7 @@ def test_insert_existing_lines():
     with open(db_path, "rb") as after_file:
         after = after_file.read()
 
-    assert before == after
+    assert before == after, "Cache was modified"
 
 
 def test_insert():