Most of my tests for a large rails app run faster than most of your tests for a large rails app and how your tests can run more like mine from tomorrow with Zeus

Do you do TDD/BDD?

Do you work on rails apps?

Do you work on large* rails apps?

*take 10 or more seconds to start up

Do you do TDD/BDD on large* rails apps?

*take 10 or more seconds to start up

Impatience is a virtue

(demo)

How?

Forks

Creating copies of processes

Speculative execution

"...do work before it is known whether that work will be needed at all, so as to prevent a delay that would have to be incurred by doing the work after it is known whether it is needed"

Zeus

Written by Burke Libbey of Shopify

Manages pool of slaves which have preloaded parts of your app and speculatively replaces them when your code changes.

(demo)

Preloading

class Zeus::Rails < Zeus::Plan
  ...
  def default_bundle
    Bundler.require(:default)
  end

  def development_environment
    Bundler.require(:development)
    ::Rails.env = ENV['RAILS_ENV'] = "development"
    require APP_PATH
    ::Rails.application.require_environment!
  end
  ...
end

Keeping fresh

Slaves are replaced when any ruby file they have loaded is changed

More than just testing

$ zeus console
$ zeus rake
$ zeus server
... 

How do I get the goodness?

Inside your rails project directory:

$ gem install zeus
$ zeus init
$ zeus start

And feel the lightning speed.

What are the alternatives?

(and why Zeus is better)