Slightly improve wsme.root coverage

wsme/tests/test_root.py

@@ -0,0 +1,15 @@
+# encoding=utf8
+
+import unittest
+
+from wsme import WSRoot
+
+
+class TestRoot(unittest.TestCase):
+    def test_default_transaction(self):
+        import transaction
+        root = WSRoot(transaction=True)
+        assert root._transaction is transaction
+
+        txn = root.begin()
+        txn.abort()