- Rake tasks should be moved out of the tasks file and into model classes to allow for easier testing with stubs and mocks. - Views can be refactored by using partials to avoid duplication and looping directly in the view. Helper methods like content_for allow setting dynamic content like page titles. - Partials, helper methods, and content_for can help DRY up views and make them easier to read and maintain.

1. You’re Doing It Wrong
Chad Pytel
cpytel@thoughtbot.com
@cpytel

2. You’re Doing It Wrong
but I love you anyway
Chad Pytel
cpytel@thoughtbot.com
@cpytel

3. Rake Tasks

4. Are you testing them?

5. What makes them hard to test?
• Scripts that live outside app
• Often have network and file access
• Often have output

6. Example Task
namespace :twitter do
task :search => :environment do
puts "Searching twitter."
Twitter.search("@cpytel").each do |result|
puts "Processing #{result.inspect}."
alert = Alert.create(:body => result)
alert.save_cache_file!
end
end
puts "All done!"
end

7. One possible way to test

8. context "rake twitter:search" do
setup do
# How slow is this going to be? Very.
@out = `cd #{Rails.root} &&
rake twitter:search 2>&1`
end

9. should "print a message at the beginning" do
assert_match /Searching/i, @out
end

10. should "find all tweets containing @cpytel" do
# this one would be based entirely on luck.
end

11. This Has Problems
• Slow
• No mocking or stubbing available
• Task isn’t in a transaction

12. Basically, no sandboxing

13. How do we fix this?

14. Rake tasks are just Ruby

15. Move it all into the Model

16. class Alert < ActiveRecord::Base
def self.create_all_from_twitter_search(output = $stdout)
output.puts "Searching twitter."
Twitter.search("@cpytel").each do |result|
output.puts "Processing #{result.inspect}."
alert = create(:body => result)
alert.save_cache_file!
end
output.puts "All done!"
end
def save_cache_file!
# Removes a file from the filesystem.
end
end

17. The Task is Nice and Skinny
namespace :twitter do
task :search => :environment do
Alert.create_all_from_twitter_search
end
end

18. Testing is Pretty Normal
# test/unit/alert_test.rb
class AlertTest < ActiveSupport::TestCase
context "create_all_from_twitter_search" do
setup do
# Make sure none of the tests below hit the
# network or touch the filesystem.
Alert.any_instance.stubs(:save_cache_file!)
Twitter.stubs(:search).returns([])
@output = StringIO.new
end

19. should "print a message at the beginning" do
Alert.create_all_from_twitter_search(@output)
assert_match /Searching/i, @output.string
end

20. should "save some cache files" do
Twitter.stubs(:search).returns(["one"])
alert = mock("alert")
alert.expects(:save_cache_file!)
Alert.stubs(:create).returns(alert)
Alert.create_all_from_twitter_search(@output)
end

21. should "find all tweets containing @cpytel" do
Twitter.expects(:search).
with("@cpytel").
returns(["body"])
Alert.create_all_from_twitter_search(@output)
end

22. We can mock and stub!

23. We can use normal tools!
• FakeWeb/WebMock
• FileUtils::NoWrite

24. In Summary
• You can test drive development of
your rake tasks
• Rake tasks should live inside a
model (or class)

25. Views

26. Know Your Helpers

27. Know How They Change

28. # Edit form
<%= form_for :user,
:url => user_path(@user),
:html => {:method => :put} do |form| %>

29. <%= form_for @user do |form| %>

30. <!-- posts/index.html.erb -->
<% @posts.each do |post| -%>
<h2><%= post.title %></h2>
<%= format_content post.body %>
<p>
<%= link_to 'Email author',
mail_to(post.user.email) %>
</p>
<% end -%>

31. Move the post content
into a partial

32. <!-- posts/index.html.erb -->
<% @posts.each do |post| -%>
<%= render :partial => 'post', :object => :post %>
<% end -%>
<!-- posts/_post.erb -->
<h2><%= post.title %></h2>
<%= format_content post.body %>
<p><%= link_to 'Email author',
mail_to(post.user.email) %></p>

33. Looping was built
into render

34. <!-- posts/index.html.erb -->
<%= render :partial => 'post', :collection => @posts %>
<!-- posts/_post.erb -->
<h2><%= post.title %></h2>
<%= format_content post.body %>
<p>
<%= link_to 'Email author',
mail_to(post.user.email) %>
</p>

35. <!-- posts/index.html.erb -->
<%= render :partial => 'post', :collection => @posts %>
<!-- posts/_post.erb -->
<h2><%= post.title %></h2>
<%= format_content post.body %>
<p>
<%= link_to 'Email author',
mail_to(post.user.email) %>
</p>

36. <%= render :partial => @posts %>

37. <%= render @posts %>

38. Dynamic Page Titles

39. <!-- layouts/application.html.erb -->
<head>
<title>
Acme Widgets : TX-300 Utility Widget
</title>
</head>

40. class PagesController < ApplicationController
def show
@widget = Widgets.find(params[:id])
@title = @widget.name
end
end
<!-- layouts/application.html.erb -->
<head>
<title>Acme Widgets : <%= @title %></title>
</head>

41. This is all View

42. There is a Helper

43. <!-- layouts/application.html.erb -->
<head>
<title>
Acme Widgets : <%= yield(:title) %>
</title>
</head>
<!-- widgets/show.html.erb -->
<% content_for :title, @widget.title %>

44. Default Title

45. <!-- layouts/application.html.erb -->
<head>
<title>
Acme Widgets : <%= yield(:title) || "Home" %>
</title>
</head>

46. What else can we use
this for?

47. <!-- layouts/application.html.erb -->
<div class="sidebar">
This is content for the sidebar.
<%= link_to "Your Account", account_url %>
</div>
<div class="main">
The main content of the page
</div>

48. <!-- layouts/application.html.erb -->
<%= yield(:sidebar) %>
<div class="main">
The main content of the page
</div>
<!-- layouts/application.html.erb -->
<% content_for :sidebar do %>
<div class="sidebar">
This is content for the sidebar.
<%= link_to "Your Account", account_url %>
</div>
<% end %>

49. Avoid Duplication

50. <!-- layouts/application.html.erb -->
<div class="sidebar">
<%= yield(:sidebar) %>
</div>
<div class="main">
The main content of the page
</div>
<!-- layouts/application.html.erb -->
<% content_for :sidebar do %>
This is content for the sidebar.
<%= link_to "Your Account", account_url %>
<% end %>

51. Conditional Sidebar
<!-- layouts/application.html.erb -->
<% if content_for?(:sidebar) -%>
<div class="sidebar">
<%= yield(:sidebar) %>
</div>
<% end -%>
<div class="main">
The main content of the page
</div>
<!-- layouts/application.html.erb -->
<% content_for :sidebar do %>
This is content for the sidebar.
<%= link_to "Your Account", account_url %>
<% end %>

53. Reviews/Refactoring