routes as explained in RoR tutorial 2nd Ed? - ruby-on-rails

Question

The author, Michael Hartl, says:
Here the rule:
get "static_pages/home"
maps requests for the URI /static_pages/home to the home action in the StaticPages controller.
How? The type of request is given, the url is given, but where is the mapping to a controller and action? My tests all pass, though.
I also tried deleting all the actions in the StaticPagesController, which just looks like this:
class StaticPagesController < ApplicationController
def home
end
def about
end
def help
end
def contact
end
end
...and my tests still pass, which is puzzling. No, I deleted all my actions like this:
class StaticPagesController < ApplicationController
end
The 2nd edition of the book(online) is really frustrating. Specifically, the section about making changes to the Guardfile is impossible to follow. For instance, if I instruct you to edit this file:
blah blah blah
dog dog dog
beetle beetle beetle
jump jump jump
and make these changes:
blah blah blah
.
.
.
go go go
.
.
.
jump jump jump
...would you have any idea where the line 'go go go' should be in the code?
And the hint for exercise 3.5-1 is flat out wrong. If the author would put up a comment section at the end of every chapter, the rails community could self-edit the book.
Tests:
require 'spec_helper'
describe "StaticPages" do
let(:base_title) { "Ruby on Rails Tutorial Sample App" }
describe "Home page" do
it "should have the h1 'Sample App'" do
visit '/static_pages/home'
page.should have_selector('h1', :text => 'Sample App')
end
it "should have the title 'Home'" do
visit "/static_pages/home"
page.should have_selector(
'title',
:text => "#{base_title} | Home")
end
end
describe 'Help page' do
it "should have the h1 'Help'" do
visit "/static_pages/help"
page.should have_selector('h1', :text => 'Help')
end
it "should have the title 'Help'" do
visit '/static_pages/help'
page.should have_selector(
'title',
:text => "#{base_title} | Help")
end
end
describe 'About page' do
it "should have the h1 'About'" do
visit '/static_pages/about'
page.should have_selector('h1', :text => 'About')
end
it "should have the title 'About'" do
visit '/static_pages/about'
page.should have_selector(
'title',
:text => "#{base_title} | About")
end
end
describe 'Contact page' do
it "should have the h1 'Contact'" do
visit '/static_pages/contact'
page.should have_selector('h1', :text => 'Contact')
end
it "should have the title 'Contact'" do
visit '/static_pages/contact'
page.should have_selector(
'title',
:text => "#{base_title} | Contact")
end
end
end

Answer 1

As you can see here:
http://guides.rubyonrails.org/routing.html#http-verb-constraints
it is just a shorthand for
match 'static_pages/home' => 'static_pages#home', :via => :get
Basically Rails infers from your url static_pages/home that you are referring to the StaticPagesController's home action.
Also, when you 'deleted' all your actions, you left the action definitions - which is what the test checks. It just checks if it can go to the home action of your staticpages controller. It doesn't matter if it does nothing, as long as it exists(at least that's what I think your tests does - care to post the tests also?)
If you delete
...
def home
end
...
from your controller, I'm pretty sure your tests will fail

Answer 2

I found an answer to this conundrum. First of all, this is a rails 'problem' not an rspec problem; if I add a route to routes.rb such as:
get "static_pages/dog"
...and then enter the url
http://localhost:3000/static_pages/dog
in my browser, rails complains:
Unknown action
The action 'dog' could not be found for StaticPagesController
Then if I add the dog action to the controller, then create a view,
everything works fine and dandy.
But if I then delete the dog action, and then use the same url,
http://localhost:3000/static_pages/dog
in my browser, this time I get a different result--instead of getting an error the view displays.
As it turns out, that inconsistent behavior is a rails 'feature' called default rendering, explained here:
http://guides.rubyonrails.org/layouts_and_rendering.html#rendering-by-default-convention-over-configuration-in-action
According to the docs, all that's needed to render a page is a route and a view--the action is optional.