'L{ResolverChain._lookup} returns a L{DomainError} failure if
its C{resolvers} list is empty.'

def test_emptyResolversList(self):

    r = ResolverChain([])
    d = r.lookupAddress('www.example.com')
    f = self.failureResultOf(d)
    self.assertIs(f.trap(DomainError), DomainError)
