- Fix long-standing bug of setting an int as sortKey return v…

…alue

... the transaction manager's ``sortKey`` method must return strings

CHANGES.rst

@@ -4,7 +4,8 @@ Changelog
 3.0.3 (unreleased)
 ------------------
 
-- Nothing changed yet.
+- Fix long-standing bug of setting an ``int`` as return value
+  for the transaction manager's ``sortKey`` method. It must be a string.
 
 
 3.0.2 (2018-03-16)

src/Shared/DC/ZRDB/TM.py

@@ -67,8 +67,8 @@ def abort(self, *ignored):
     tpc_abort = abort
 
     # Most DA's talking to RDBMS systems do not care about commit order, so
-    # return the constant 1
-    _sort_key = 1
+    # return a constant. Must be a string according to ITransactionManager.
+    _sort_key = '1'
 
     def sortKey(self, *ignored):
         """ The sortKey method is used by the transaction subsystem to have a
@@ -77,7 +77,7 @@ def sortKey(self, *ignored):
         return self._sort_key
 
     def setSortKey(self, sort_key):
-        self._sort_key = sort_key
+        self._sort_key = str(sort_key)
 
 class Surrogate:
 

src/Shared/DC/ZRDB/tests/testTM.py

@@ -18,12 +18,17 @@ class TestTM(TestCase):
 
     def test_sortKey(self):
         tm = TM()
-        # the default Transaction Manager should have .sortKey() of 1 for
-        # backward compatibility
-        self.assertEqual(tm.sortKey(), 1)
+        # the default Transaction Manager should have .sortKey() of '1' for
+        # backward compatibility. It must be a string according to the
+        # ITransactionManager interface.
+        self.assertEqual(tm.sortKey(), '1')
+
         # but the sortKey() should be adjustable
-        tm.setSortKey(())
-        self.assertEqual(tm.sortKey(), ())
+        tm.setSortKey('2')
+        self.assertEqual(tm.sortKey(), '2')
+
+        tm.setSortKey([])
+        self.assertEqual(tm.sortKey(), '[]')
 
 def test_suite():
     return TestSuite((makeSuite(TestTM),))