Notes posted by henning

Getting (n..end) reloaded

You can do

array[n..-1]

How to test callback methods

When testing callback methods, try to test the callback chain separate from its implementation.

Say this is your model:

class Project

  belongs_to :owner
  has_many :milestones

  after_save :create_milestones
  after_save :notify_owner

  private

  def notify_owner
    owner.project_created!
  end

  def create_milestones
    milestones.create(:name => 'Milestone 1')
  end

end

You should write your spec like this:

describe Project do

  describe 'create_milestones' do
    it 'should create an initial milestone' do
      project = Project.new
      project.milestones.should_receive(:create)
      project.send(:create_milestones)
    end
  end

  describe 'notify_owner' do
    it 'should notify its owner' do
      project = Project.new(:owner => mock_model(User))
      project.owner.should_receive(:project_created!)      
      project.send(:notify_owner)
    end
  end

  describe 'after_save' do
    it 'should run the proper callbacks' do
      project = Project.new
      project.should_receive(:create_milestones)
      project.should_receive(:notify_owner)
      project.run_callbacks(:after_save)
    end
  end

end

Here is some more advice on how to test callback methods in Rails:

http://gem-session.com/2010/03/how-to-test-callback-methods-in-rails

Using models in your migration

Here is some advice how to call your models in a migration without shooting yourself in the foot:

http://gem-session.com/2010/03/how-to-use-models-in-your-migrations-without-killing-kittens

Basically you can inline models into your migrations to decouple them from changes in your model:

class AddCurrentToVendor < ActiveRecord::Migration

  class Vendor < ActiveRecord::Base
  end

  class Article < ActiveRecord::Base
    has_many :vendors, :class_name => 'AddCurrentToVendor::Vendor', :order => 'created_at'
  end

  def self.up
    add_column :vendors, :current, :boolean
    Article.all.each do |article|
      article.vendors.first.andand.update_attribute(:current, true)
    end
  end

  def self.down
    remove_column :vendors, :current
  end
end

How to test custom error pages

Here is some advice for testing custom error pages using Webrat and Cucumber:

http://gem-session.com/2010/03/testing-your-custom-error-pages-with-webrat-and-cucumber