Fast Rails Tests -- Test in Isolation

burro.rb

class Burro < ActiveRecord::Base

  #guacamole defined on schema

  def delicious?
    BurroDeliciousPolicy.new(self).delicious?
  end

end

burro_delicious_policy.rb

require_relative '../../app/models/burro_delicious_policy'

describe BurroDeliciousPolicy do

  it "should be delicioso if it has guacamole" do
    policy = BurroDeliciousPolicy.new(double(:guacamole? => true))
    policy.delicious?.should be_true
  end

  it "should not be delioso if we lack the guac" do
    policy = BurroDeliciousPolicy.new(double(:guacamole? => false))
    policy.should_not be_delicious
  end

end

burro_delicious_policy_spec.rb

require_relative '../../app/models/burro_delicious_policy'

describe BurroDeliciousPolicy do

  it "should be delicioso if it has guacamole" do
    policy = BurroDeliciousPolicy.new(double(:guacamole? => true))
    policy.delicious?.should be_true
  end

  it "should not be delioso if we lack the guac" do
    policy = BurroDeliciousPolicy.new(double(:guacamole? => false))
    policy.should_not be_delicious
  end

end

burro_spec.rb

module ActiveRecord
  class Base; end
end

class Burro < ActiveRecord::Base
  attr_accessor :guacamole
  def guacamole?
    @guacamole
  end
end

require_relative '../../app/models/burro'
require_relative '../../app/models/burro_delicious_policy'

describe Burro do

  it "is delicious with guacamole" do

    subject.guacamole = true
    subject.should be_delicious

  end

  it "is not delicious without guacamole" do

    subject.guacamole = false
    subject.should_not be_delicious

  end
end