'Verify that L{components.registerAdapter} raises L{ValueError} if the
from-type/interface and to-interface pair is not unique.'

def _duplicateAdapterForClassOrInterface(self, original):

    firstAdapter = (lambda o: False)
    secondAdapter = (lambda o: True)
    components.registerAdapter(firstAdapter, original, ITest)
    self.assertRaises(ValueError, components.registerAdapter, secondAdapter, original, ITest)
    self.assertIs(components.getAdapterFactory(original, ITest, None), firstAdapter)
