'Append two messages and check inside the QoS object that they
were put into the internal data structures correctly'

def test_append(self):

    qos = self.qos_no_limit
    (m1, m1_tag) = self.mock_message_factory()
    (m2, m2_tag) = self.mock_message_factory()
    qos.append(m1, m1_tag)
    length_not_yet_acked = len(qos._not_yet_acked)
    assert (length_not_yet_acked == 1)
    checked_message1 = qos._not_yet_acked[m1_tag]
    assert (m1 is checked_message1)
    qos.append(m2, m2_tag)
    length_not_yet_acked = len(qos._not_yet_acked)
    assert (length_not_yet_acked == 2)
    checked_message2 = qos._not_yet_acked[m2_tag]
    assert (m2 is checked_message2)
