'Features known to have default values are reported as being present by
L{irc.ServerSupportedFeatures.hasFeature}, and their value defaults
correctly, when they don\'t appear in an ISUPPORT message.'

def _testFeatureDefault(self, name, features=None):

    default = irc.ServerSupportedFeatures()._features[name]
    if (features is None):
        features = [('DEFINITELY_NOT', 'a_feature')]
    supported = self._parse(features)
    self.assertTrue(supported.hasFeature(name))
    self.assertEqual(supported.getFeature(name), default)
