Use more importorskip.

habnabit · habnabit · commit 19f75631147f · 2014-04-15T11:56:14.000-04:00
diff --git a/examples/protocol/test_netstrings.py b/examples/protocol/test_netstrings.py
@@ -1,9 +1,11 @@
-from twisted.test.proto_helpers import StringTransport
-
 import parsley
 import pytest
 import netstrings
 
+proto_helpers = pytest.importorskip('twisted.test.proto_helpers')
+StringTransport = proto_helpers.StringTransport
+
+
 netstringGrammar = parsley.makeGrammar(netstrings.grammar, {})
 
 def stringParserFromRule(rule):
