fix test and a missing X509_REVOKED_dup call
diff --git a/tests/test_crypto.py b/tests/test_crypto.py
index 03b94b9..e90c868 100644
--- a/tests/test_crypto.py
+++ b/tests/test_crypto.py
@@ -3186,6 +3186,8 @@
         """
         crl = CRL()
         revoked = Revoked()
+        revoked.set_serial("01")
+        revoked.set_rev_date(b"20160310020145Z")
         crl.add_revoked(revoked=revoked)
         self.assertTrue(isinstance(crl.get_revoked()[0], Revoked))