--- a/tests/unit.py	Tue Mar 27 09:40:15 2012 -0700
+++ b/tests/unit.py	Tue Mar 27 09:52:51 2012 -0700
@@ -52,12 +52,15 @@
         self.assertTrue(isinstance(json_provider, configuration.JSON))
 
         # serialize to a temporary file
-        filename = tempfile.mktemp()
+        filename = tempfile.mktemp(suffix='.json')
+        self.assertFalse(os.path.exists(filename))
         config = {'browser_path': '/home/jhammel/bin/firefox',
                   'activeTests':  ['ts']}
         example(config)
         config['test_timeout'] = 1200 # default
         self.assertEqual(config, example.config)
+        example.serialize(filename)
+        self.assertTrue(os.path.exists(filename))
         if os.path.exists(filename):
             os.remove(filename)