Peter Souter showed me a recent PR for the puppet-approved jenkins module where he parallelized the rspec tests. When there are a large number of tests in separate files, it can take a lot of time when run in series. Parallelizing the tests MAY offer a speed improvement; in Peter’s case, it reduced the time by almost 50%. With a small number of tests, or when an overwhelming percentage of the tests are in a single file, there may be no benefit or even a decrease in performance, so be sure to test out its effects before committing to it. It’s a pretty simple change, but let’s look at it in some detail anyway.

Gemfile

In your Gemfile, you need to add one line:

gem 'parallel_tests'

Continue reading →