fix: add util module, w/ model_transaction_query()

just a basic implementation, will have to improve later

tests/test_util.py

@@ -0,0 +1,40 @@
+# -*- coding: utf-8; -*-
+
+from unittest import TestCase
+
+import sqlalchemy_continuum as continuum
+
+from wutta_continuum import util as mod
+from wutta_continuum.testing import VersionTestCase
+
+
+class TestRenderOperationType(TestCase):
+
+    def test_basic(self):
+        self.assertEqual(
+            mod.render_operation_type(continuum.Operation.INSERT), "INSERT"
+        )
+        self.assertEqual(
+            mod.render_operation_type(continuum.Operation.UPDATE), "UPDATE"
+        )
+        self.assertEqual(
+            mod.render_operation_type(continuum.Operation.DELETE), "DELETE"
+        )
+
+
+class TestModelTransactionQuery(VersionTestCase):
+
+    def test_basic(self):
+        model = self.app.model
+
+        user = model.User(username="fred")
+        self.session.add(user)
+        self.session.commit()
+
+        query = mod.model_transaction_query(user)
+        self.assertEqual(query.count(), 1)
+        txn = query.one()
+
+        UserVersion = continuum.version_class(model.User)
+        version = self.session.query(UserVersion).one()
+        self.assertIs(version.transaction, txn)