Many of us have several existing 2.x applications and would want to upgrade without pulling our hair because we can't figure out something or we are wary of consuming too much time. I'm about to post several links where you could find useful advice on upgrading Rails 3. Feel free to share other links if you know some.

Question: is it worth it to upgrade?

It's definitely worth it. There is no logical reason for staying "behind" (other than money).

Obviously, an application that has a test suite or has been developed using TDD (Test-Driven Development) or BDD (Behaviour-Driven Development) is much is easier to upgrade than apps that don't.

What has changed in RSpec for Rails 3?
Not much.

In Rails 2.x, we have this functional test:

 require 'spec_helper'

describe PostsController do
  integrate_views
  fixtures :posts
  fixtures :users
  setup :activate_authlogic

  def mock_post(stubs={})
    @mock_post ||= mock_model(Post, stubs).as_null_object
  end

  describe "GET index" do

     before do
        require_admin
     end

    it "assigns all posts as @posts" do
      Post.stub(:all) { [mock_post] }
      get :index
      assigns(:posts).should eq([mock_post])
    end
  end

end 

If we'd like it to work for Rails 3, we just need to change one thing.

require 'spec_helper'

describe PostsController do
  render_views
  fixtures :posts
  fixtures :users
  setup :activate_authlogic

  def mock_post(stubs={})
    @mock_post ||= mock_model(Post, stubs).as_null_object
  end

  describe "GET index" do

     before do
        require_admin
     end

    it "assigns all posts as @posts" do
      Post.stub(:all) { [mock_post] }
      get :index
      assigns(:posts).should eq([mock_post])
    end
  end

end

I really appreciate that many developers share their experience on how they successfully upgraded their applications to 3.x. One of them is Greg Moreno. He is founder of Propsify. He's a Filipino developer based in Canada who'll come back to the Philippines in September for RailsJam events. Please find time to check out the website (which I designed) for details about the events:

RailsJam

These are the most useful and concise posts I've seen on upgrading a 2.x app to 3.x:

Rails 3 upgrade part 1: Booting the application

Rails 3 upgrade part 2: Routes

Rails 3 upgrade part 3: Code fixes, views, and forms

I also find the Rails 3 Upgrade handbook PDF (not free) very useful. It's like a manual that shows everything (or nearly everything) that's deprecated in Rails 3.

Rails 3 Upgrade Handbook

Also Rails 3 works well or better for Ruby 1.9.2. So you have to install RVM to use with 1.9.2 version.

Someone asked me this, what is "g" in Rails 3?

It's simply an alias for "generate."

rails g
Usage: rails generate GENERATOR [args] [options]

General options:
  -h, [--help]     # Print generators options and usage
  -p, [--pretend]  # Run but do not make any changes
  -f, [--force]    # Overwrite files that already exist
  -s, [--skip]     # Skip files that already exist
  -q, [--quiet]    # Supress status output

Please choose a generator below.

Rails:
  controller
  generator
  helper
  integration_test
  mailer
  migration
  model
  observer
  performance_test
  plugin
  resource
  scaffold
  scaffold_controller
  session_migration
  stylesheets

Authlogic:
  authlogic:session
  authlogic:session

Cucumber:
  cucumber:feature
  cucumber:install

Datamapper:
  datamapper:migration
  datamapper:model
  datamapper:observer

Erb:
  erb:controller
  erb:mailer
  erb:scaffold

Erubis:
  erubis:controller
  erubis:scaffold

FactoryGirl:
  factory_girl:model

Formtastic:
  formtastic:scaffold

FriendlyId:
  friendly_id

Haml:
  haml:install

Jquery:
  jquery:install

Koala:
  koala:install

Machinist:
  machinist:model

Mongomapper:
  mongomapper:model
  mongomapper:observer

Mustache:
  mustache:controller
  mustache:install
  mustache:scaffold

Rspec:
  rspec:install

Shoulda:
  shoulda:controller
  shoulda:model

SimpleForm:
  simple_form:scaffold

TestUnit:
  test_unit:controller
  test_unit:helper
  test_unit:integration
  test_unit:mailer
  test_unit:model
  test_unit:observer
  test_unit:performance
  test_unit:plugin
  test_unit:scaffold

Hope this was useful.

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Hello! I am Kat. I've been a developer for several years. When I'm not sitting down, reading and working for long hours, I am traveling to some place of interest.
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