Fix NoMethodError for --pr option (caused by module_options = nil) / introduce --noop

[bittner]

Adds --noop support for the --pr option.

Adds feature tests for both GitHub PRs and GitLab MRs to prove the bug reported with issue #187.

Fixes #187

[bittner]

This should be ready for merging now. Can you take a look again? Thanks!

[ekohl]

I wonder if the following pattern would be easier:

do_prep_work

if options[:noop]
  $stdout.puts "Using no-op. Would do real work"
  return
end

do_real_work

I don't know the answer - there are really good arguments for both.

[bittner]

I wonder if the following pattern would be easier:

I have applied your suggested changes to the GitLab pr module. That makes the code structure flatter, which is better. Nice, thank you!

In the GitHub pr module the code is different: The code, which sets the labels, needs to run afterwards and has a separate :noop clause. It might be a good idea to align the two implementations, e.g. while fixing issue #176, so that code could also benefit from a flatter structure.

[bittner]

Any more corrections needed? Otherwise, I'd be happy if we could merge the changes. 🤞

[raphink]

I wonder if the following pattern would be easier:

do_prep_work

if options[:noop]
  $stdout.puts "Using no-op. Would do real work"
  return
end

do_real_work

I don't know the answer - there are really good arguments for both.

I was going to say the same actually. I prefer short circuits for this kind of logic.

[ekohl]

@raphink I think this looks good, but since reviewed it too I'll let you do the final review.

[raphink]

Ok for me then

[bittner]

Thank you @raphink and @ekohl! 🥇