update cnfvar unittest for python 3

diff --git a/test/cnfvar_unittest.py b/test/cnfvar_unittest.py
index 37e5fe3..45f6c60 100755 (executable)
--- a/test/cnfvar_unittest.py
+++ b/test/cnfvar_unittest.py
@@ -341,8 +341,8 @@ class CnfVarUnittest(unittest.TestCase):
         try:
             with open("/dev/null", "w") as devnull:
                 cnfvar.print_cnf(demo_invalid_cnfvar, out=devnull)
-        except cnfvar.InvalidCNF, exn:
-            print "Caught the duplicate line, bravo!"
+        except cnfvar.InvalidCNF:
+            print ("Caught the duplicate line, bravo!")
 
     def test_read_json(self):
         cnf = cnfvar.read_cnf_json(demo_jsoncnf)