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Tests ruby code as it changes, in parallel
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test:loop - continuous testing with fork/eval

test:loop is a Rake task that continously tests changes in your Ruby application in an efficient manner, using a fork/eval approach that:

  1. Absorbs the test execution overhead into the main Rake process.
  2. Forks to evaluate your test files directly and without overhead.

It relies on file modification times to determine what parts of your Ruby application have changed and then uses Rake's String#pathmap function to determine which test files in your test suite correspond to those changes.


  • Tests CHANGES in your Ruby application; does NOT run all tests every time.

  • Supports Test::Unit, RSpec, or any other testing framework that is utilized by your application's test/test_helper.rb and spec/spec_helper.rb files.

  • Reabsorbs test execution overhead if the test or spec helper file changes.

  • Mostly I/O bound, so you can have it always running without CPU slowdowns.


As a Ruby on Rails plugin:

rails plugin install git://  # Rails >= 3
script/plugin install git:// # older Rails

As a regular Ruby library, download the lib/tasks/test:loop.rake file and require it into your Rakefile or use it directly by passing it to rake -f.


rake test:loop

  • Pass "RUN=1" as a command-line argument to run all tests initially, even if there are no changes in your Ruby application.

  • To stop the task after it has begun running, press Control-C or kill the process manually.


See the LICENSE file for details.

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