#413 Fast Tests pro

Apr 10, 2013 | 17 minutes | Performance, Testing, Tools

A slow test suite can put a damper on test-driven development. In this episode I show a variety of ways to optimize specs including: selective testing, preloading Rails, and testing outside of Rails.

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          terminal
        
time bundle exec rake spec:models
time bundle exec rspec spec/models
bundle binstubs rspec-core
time bin/rspec spec/models
zeus start
time zeus test spec/models
SLOW_SPECS=true rspec spec/models
rspec -p spec
rake parallel:create
rake parallel:prepare
zeus-parallel_tests init
zeus parallel_rspec spec
guard
bin/rspec spec/lib

          Gemfile
        
group :test, :development do
  gem "rspec-rails"
  gem "parallel_tests"
  gem "zeus-parallel_tests"
end

group :test do
  gem "factory_girl_rails"
  gem "capybara"
  gem "guard-rspec"
  gem "rb-fsevent"
  gem "zeus"
end

          Guardfile
        
guard 'rspec', all_on_start: false, all_after_pass: false, zeus: true, parallel: true, bundler: false

          spec_helper.rb
        
config.treat_symbols_as_metadata_keys_with_true_values = true
config.filter_run focus: true
config.run_all_when_everything_filtered = true

config.filter_run_excluding :slow unless ENV["SLOW_SPECS"]

# config.before(:each) { GC.disable }
# config.after(:each) { GC.enable }
config.before(:all) { DeferredGarbageCollection.start }
config.after(:all) { DeferredGarbageCollection.reconsider }

          spec/support/deferred_garbage_collection.rb
        
class DeferredGarbageCollection

  DEFERRED_GC_THRESHOLD = (ENV['DEFER_GC'] || 15.0).to_f

  @@last_gc_run = Time.now

  def self.start
    GC.disable if DEFERRED_GC_THRESHOLD > 0
  end

  def self.reconsider
    if DEFERRED_GC_THRESHOLD > 0 && Time.now - @@last_gc_run >= DEFERRED_GC_THRESHOLD
      GC.enable
      GC.start
      GC.disable
      @@last_gc_run = Time.now
    end
  end
end