gprs-ns/test: Add test_sgsn_reset_invalid_state

This tests the behaviour for a certain combination of messages and
packet losses that can put the NS-VC object into an undefined state.

In that state, the peer's ALIVE messages are properly answered, but
the local test procedure has stopped, incoming unitdata PDUs are
answered by STATUS(NS-VC blocked) and the unblocking procedure is not
initiated.

Ticket: OW#1312
Sponsored-by: On-Waves ehf
2 files changed