Set up a fast rails test environment

fast_rails_test_env.md

Use sqlite in memory db :

config/database.yml

  test:
    adapter: sqlite3
    database: ":memory:"

Setup Spring configuration to run with in memory db :

config/spring.rb

  if defined?(Spring)
    Spring.after_fork do
      load "#{Rails.root.to_s}/config/initializers/in_memory_db.rb"
    end
  end

Load schema on environment startup

config/initializers/in_memory_db.rb

  def in_memory_database?
  Rails.env == "test" and
      ActiveRecord::Base.connection.adapter_name.downcase.include?('sqlite') and
      Rails.configuration.database_configuration['test']['database'] == ':memory:'
  end

  if in_memory_database?
    require 'active_record/migration'
    ActiveRecord::Migration.verbose = false
    puts "creating sqlite in memory database"
    load "#{Rails.root}/db/schema.rb"
  end