Integration test for stream-events

[Profpatsch]

We broke the stream-events in the last update, so we should create some integration tests that call the lorri executable

• test the different --kind settings
• check that all kinds of events are really shown.

What will be interesting:

• how to start a lorri service and stop it as soon as an event arrives
• how to trigger events in lorri without depending on too many nix internals

[nyarly]

how to start a lorri service and stop it as soon as an event arrives

You don't want the service to exit after the event, right? You want to get the events actually streamed out first, and then kill the service. Exiting the stream-events process is trickier, but a timeout is called for regardless. In a testing context, a watchdog timer seems appropriate.

how to trigger events in lorri without depending on too many nix internals

cp start-version shell.nix
lorri internal ping shell.nix
cp updated-version shell.nix
lorri internal stream-events --kind 
kill $DAEMON #?