I am only asking about flight testing civilian jets, not military ones. I know that all test pilots have to be equipped with a parachute, so I wonder was there any incident where the test pilots and test engineers had to leave the plane during the flight, and managed to reach the earth? Alive or dead.
Do civilian space ships count?
In the VSS Enterprise crash the captain survived. The plane broke up around him and he was able to unstrap his seat after which his parachute automatically deployed. The co-pilot died in the crash.
Yes. Here is a (long) video of a test pilot spinning a Bonanza with a cockpit POV. He ends up bailing out. Skip to 11:30 to watch the entry.
Ovbiously not a jet, but maybe it's close to what you're looking for.
During the early development flight tests of the Challenger, an aircraft was trapped in a deep stall. Two crew members bailed out, but the final crew member did not survive the bail out.
In the remote-controlled crash of a 727, https://en.wikipedia.org/wiki/2012_Boeing_727_crash_experiment, the crew (and some camera-men) left by parachute...
Quoting from the Aviation Safety Network:
The HansaJet prototype was in the midst of stall configuration tests at 22,000 [feet,] when it attained an extreme angle of attack resulting in a superstall. The airplane then entered an uncontrollable flat spin. Two crew members were able to parachute to safety.