Failing gracefully if twisted isn't installed.

Author: habnabit

ometa/test/test_protocol.py

@@ -1,7 +1,13 @@
-from twisted.trial import unittest
+try:
+    from twisted.trial import unittest
+    from ometa.protocol import ParserProtocol
+except ImportError:
+    import unittest
+    skip = "twisted not installed or usable"
+else:
+    skip = None
 
 from ometa.grammar import OMeta
-from ometa.protocol import ParserProtocol
 from ometa.runtime import ParseError
 
 
@@ -59,6 +65,8 @@ def abortConnection(self):
 
 
 class ParserProtocolTestCase(unittest.TestCase):
+    skip = skip
+
     def setUp(self):
         self.protocol = ParserProtocol(
             testGrammar, SenderFactory, StateFactory, {})

parsley.py

@@ -1,7 +1,6 @@
 import functools
 
 from ometa.grammar import OMeta
-from ometa.protocol import ParserProtocol
 from ometa.runtime import ParseError, EOFError, OMetaBase, expected
 from terml.parser import parseTerm as term
 from terml.nodes import termMaker
@@ -59,6 +58,7 @@ def makeProtocol(source, senderFactory, stateFactory, bindings=None,
     Create a Protocol implementation from a Parsley grammar.
     """
 
+    from ometa.protocol import ParserProtocol
     if bindings is None:
         bindings = {}
     grammar = OMeta(source).parseGrammar(name)