DEV: Add a new way to run specs in parallel with better output

[danielwaterworth]

This PR:

1. adds a new executable, bin/interleaved_rspec which works much like
   rspec, but runs the tests in parallel.

2. adds a rake task, rake interleaved:spec which runs the whole test
   suite.

3. makes autospec use this new wrapper by default. You can disable this
   by running PARALLEL_SPEC=0 rake autospec.

It works much like the parallel_tests gem (and relies on it), but
makes each subprocess use a machine-readable formatter and parses this
output in order to provide a better overall summary.

(It's called interleaved, because parallel was taken and naming is
hard).

[eviltrout]

Overall this is excellent, good job.

I would like to be annoying though and suggest an alternative name from InterleavedTests which seems a bit technical and hard to remember/type.

How about something like:

• FastTests
• TurboTests
• QuickTests
• RapidTests

[danielwaterworth]

@eviltrout, I appreciate the comments! I will fix those things tomorrow.

[SamSaffron]

Some questions:

• Can we upstream this to the parallel test gem?

• With @eviltrout on changing the name of the binary... maybe bin/rspec_parallel ?

• From my perspective this is how "parallel tests" should work I am not sure how much of the interleaved naming we should carry short of internal implementation details.

• PARALLEL_SPEC=0 rake autospec is a very strange way of enabling this. I think PARALLEL_SPEC=1 rake autospec to enable and then remove support for old parallel test integration it had, we only need this 1 pattern.

Looking forward to merging this in! Awesome work.

[danielwaterworth]

• Can we upstream this to the parallel test gem?

I've filed an issue in the parallel_tests issue tracker to discuss this.

• With @eviltrout on changing the name of the binary... maybe bin/rspec_parallel ?

• From my perspective this is how "parallel tests" should work I am not sure how much of the interleaved naming we should carry short of internal implementation details.

Ok

• PARALLEL_SPEC=0 rake autospec is a very strange way of enabling this. I think PARALLEL_SPEC=1 rake autospec to enable and then remove support for old parallel test integration it had, we only need this 1 pattern.

The default is now parallel with PARALLEL_SPEC=0 being used to fallback to regular rspec. I can switch this to use SERIAL_SPEC=1 instead if you'd like.

[SamSaffron]

I prefer to have this opt in for a few weeks, so do this for now:

if ENV["PARALLEL_SPEC"] == '1'

[SamSaffron]

OK ... I want to try this out... we can refine in followup commits.

[discoursebot]

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