Activate verbosity for assertions

xml_marshaller/xml_marshaller.py

@@ -622,7 +622,9 @@ def test(load, loads, dump, dumps, test_values,
     file.seek(0)
     output2 = load(file)
     if do_assert:
-      assert item == output and item == output2 and output == output2
+      assert item == output,  '%r %r' % (item, output)
+      assert item == output2 , '%r %r' % (item, output2)
+      assert output == output2, '%r %r' % (output, output2)
 
 
 # Classes used in the test suite