TST: add test for query and some minor changes

unittests/test_identifiable_adapters.py

@@ -47,7 +47,8 @@ def test_create_query_for_identifiable():
         .add_property("f", value=datetime(2020, 10, 10))
         .add_property("g", value=True)
         .add_property("h", value=db.Record(id=1111))
-        .add_property("i", value=[2222, db.Record(id=3333)]))
+        .add_property("i", value=db.File(id=1112))
+        .add_property("j", value=[2222, db.Record(id=3333)]))
     assert (query.lower() == "find record b with name='a' and 'c'='c' and 'd'='5' and 'e'='5.5'"
-            " and 'f'='2020-10-10t00:00:00' and 'g'='true' and 'h'='1111' and 'i'='2222' and "
-            "'i'='3333' ")
+            " and 'f'='2020-10-10t00:00:00' and 'g'='true' and 'h'='1111' and 'i'='1112' and "
+            "'j'='2222' and 'j'='3333' ")