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

def test_errReceived(self):

    received = []
    class ErrProtocol(StubProcessProtocol, ):
        def errReceived(self, data):
            received.append(data)
    bytesToSend = 'bytes'
    p = ErrProtocol()
    p.childDataReceived(2, bytesToSend)
    self.assertEqual(received, [bytesToSend])
