'L{ListOf.toBox} silently omits serializing any argument with a
value of L{None} that is designated as optional for the protocol.'

def test_optionalArgumentWithNoneValueOmitted(self):

    stringList = amp.ListOf(amp.Integer(), optional=True)
    strings = amp.AmpBox()
    stringList.toBox('omitted', strings, {'omitted': None}, None)
    self.assertEqual(strings, {})
