MGCP_Test: add tests to verify actual RTP flows

The test coverage of the RTP aspects of the MGW is currently very
minima. Lets add a few more testcase to verify RTP behaves as
expected in various situations.

- Add testcase TC_one_crcx_receive_only_rtp:
  Test recvonly mode of the MGW. All packets must be absorbed by
  the MGW, no packets must come back.

- Add testcase TC_one_crcx_loopback_rtp:
  Test loopback mode of the MGW. All packet sent to the MGW must
  come back.

- Add testcase TC_two_crcx_and_rtp_bidir:
  We already test unidirectional transmissions. This test does
  the same as TC_two_crcx_and_rtp but for both directions.

- Add testcase TC_two_crcx_mdcx_and_rtp:
  Simulate a typical behaviour of a normal call. First create
  two half open connections and complete the connections later
  using MDCX.

- Add testcase TC_two_crcx_and_unsolicited_rtp:
  Test what happens when a RTP packets from rogue source are mixed
  into the RTP stream.

- Add testcase TC_two_crcx_and_one_mdcx_rtp_ho:
  Test a typical handover situation. An existing connection is
  handovered to another source on one end but the old source will
  keep transmitting for a while.

Change-Id: I556a6efff0e74aab897bd8165200eec36e46629f
Closes: OS#2703
3 files changed