Suspect

If you have slow tests, you need a troubleshooting strategy. It takes a lot of effort to get rid of this smell. In meantime it is good to have a palliative. Suspect provides such a band-aid. The gem collects test results along with VCS (Git) status and uses harvested data to select a subset of test files to be run.

Tags

• Test Smells
• Slow Tests
• RSpec
• TDD
• BDD
• Anti-patterns

Installation

Add this line to your application's Gemfile:

gem 'suspect'

And then execute:

$ bundle

Or install it yourself as:

$ gem install suspect

Add to RSpec helper file:

# spec/spec_helper.rb
require 'suspect/rspec_listener'

RSpec.configure do |config|

  ::Suspect::RSpecListener.setup_using config

Create a rake file:

# lib/tasks/suspect.rake

namespace :suspect do
  desc 'run suspect test files in parallel'
  task :parallel_rspec do
    paths = ::Suspect::Prediction::Default.paths

    if paths.any?
      puts "#{paths.size} test file(s) are going to be run..."
      puts `bundle exec parallel_rspec #{paths.join(' ')} -n 7`
    else
      puts 'No test files found to be run'
    end
  end
end

Usage

Suspect is conceptually divided into two parts:

• data gathering
• failure prediction

Gathering

As soon as the gem is added to Gemfile and Suspect::RSpecListener.setup_using config is invoked in spec/spec_helper.rb, the gathering part is up and running. Each time you run specs, results are stored for further usage. Harvested data is stored under suspect/ folder in *.suspect files. Adding *.suspect files under source control allows data sharing between project members.

Prediction

Suspect::Prediction::Default.paths returns a list of spec files which are more likely to fall. The installation section above contains a simple rake task for the prediction phase. Fill free to modify the task to better meet your requirements.

Assumptions

• A project uses:
  • Git
  • RSpec

TODO

• Basic error handling (especially for file operations)
• Enhanced Rake task examples in README:
  • run rspec taking collected data into account
  • run parallel_tests taking collected data into account
• More sophisticated strategies for finding test files to be run

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/suspect. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.