Return correct exit code when server fails to start

[michalholasek]

🚀 Why this change?

This PR fixes the issue with wrong CLI exit code when running Dredd with incorrect argument to --server command (reported in #818).

📝 Related issues and Pull Requests

Closes #838

✅ What didn't I forget?

• To write docs - N/A
• To write tests
• To put Conventional Changelog prefixes in front of all my commits and run npm run lint

[honzajavorek]

Failing in all builds:

  Babysitting Child Processes
    when gracefully terminated by childProcess.signalTerm()
      process without support for graceful termination
        ...

TypeError: Cannot read property 'indexOf' of undefined

[michalholasek]

@honzajavorek Fixed.

[honzajavorek]

I like the changes 👍 Great job. I wonder what your replies to my comments would be, otherwise I'd approve this.

[honzajavorek]

I just realized we probably want to do this in case of any kind of error happening to the backend server child process. If the process errors, Dredd cannot ensure the testing will make sense, and it should stop testing and terminate. So I propose we actually keep @serverProcess.on 'error' here. What do you think?

[michalholasek]

I have no problem with that, we can differentiate between different type of runtime errors in single error handler hub.

[michalholasek]

Reflected in ab90347.

[honzajavorek]

I just realized there's one more side to the problem: The process starts, but Dredd isn't able to connect to it using HTTP. Looking into coverage, this scenario seems to be untested:

transaction-runner.coffee

---

I hope it would still work as expected (Dredd fails all tests and it ends with exit code 1), but it would be awesome if we had a test for that as well. What do you think?

It should be fairly easy to test, with the same approach, just spawning an existing script, which hangs the same way as server would do (endless setTimeout loop?), but which doesn't handle HTTP in any way. Maybe there's even already a script like that in test/fixtures, I haven't take a look.

[michalholasek]

Agree, I'll have a look.

[honzajavorek]

My attempt is in #862. If the section screenshoted above won't get green, then the test is useless and my PR should get closed.

[honzajavorek]

🚀