Allowed for arbitrary length strings from urandom

letsencrypt/plugins/manual_test.py

@@ -51,7 +51,7 @@ class ManualAuthenticatorTest(unittest.TestCase):
     @mock.patch("__builtin__.raw_input")
     def test_perform(self, mock_raw_input, mock_verify, mock_urandom,
                      mock_stdout):
-        mock_urandom.return_value = "foo"
+        mock_urandom.side_effect = nonrandom_urandom
         mock_verify.return_value = True
 
         resp = challenges.SimpleHTTPResponse(tls=False)
@@ -106,5 +106,10 @@ class ManualAuthenticatorTest(unittest.TestCase):
         mock_killpg.assert_called_once_with(1234, signal.SIGTERM)
 
 
+def nonrandom_urandom(num_bytes):
+    """Returns a string of length num_bytes"""
+    return "x" * num_bytes
+
+
 if __name__ == "__main__":
     unittest.main()  # pragma: no cover