Rails%203%20In%20Action

478 CHAPTER 17 Engines
2. Goes through middleware
stack until...
It’s the same cycle, except this time the routing code has determined this request
should be handled by the engine, rather than the application.
We’ve talked long enough about the theory of an engine, and you’ve learned some
key concepts. An engine is a miniature application that provides some functionality,
and it’s routed like a normal application would be, providing you’ve mounted it in
your application’s config/routes.rb file.
It’s time to put all this theory into practice.
17.4 Setting up a testing environment
Before you can get down to writing any tests, you’re going to need to set up the environment
to do that. For a change, you’re not going to be writing tests for your engine
using Cucumber. Instead, you’re going to be using RSpec and Capybara. It’s always
good to get a different perspective on testing, as not everyone agrees on the One True
Way TM of doing things. The syntax for this RSpec and Capybara is still easy going, however,
as shown by this example:
require 'spec_helper'
1. Request comes in for
GET /forem/forums
Middleware #1
Middleware #n
3. Routes receive request
Browser
Server
... Application Engine
Routes
4. What route is it?
GET /forem/forums
7. Response goes out
describe "topics" do
it "creating a new one" do
visit topics_path
click_link "New Topic"
fill_in "Subject", :with => "First topic!"
6. Engine responds
5. That route goes to
the engine!
Figure 17.4
Routing cycle of an engine