'Test jellying C{sets.ImmutableSet}: it should serialize to the same
thing as L{frozenset} jelly, and be unjellied as L{frozenset} if
available.'

def test_oldImmutableSets(self):

    inputList = [jelly._sets.ImmutableSet([1, 2, 3])]
    inputJelly = jelly.jelly(inputList)
    self.assertEqual(inputJelly, jelly.jelly([frozenset([1, 2, 3])]))
    output = jelly.unjelly(inputJelly)
    self.assertEqual(list(inputList[0]), list(output[0]))
    if (frozenset is jelly._sets.ImmutableSet):
        self.assertIsInstance(output[0], jelly._sets.ImmutableSet)
    else:
        self.assertIsInstance(output[0], frozenset)
