'Similar to L{test_inConnectionLost}, but for stderr.'

def test_errConnectionLost(self):

    lost = []
    class ErrLostProtocol(StubProcessProtocol, ):
        def errConnectionLost(self):
            lost.append(None)
    p = ErrLostProtocol()
    p.childConnectionLost(2)
    self.assertEqual(lost, [None])
