How to test Rails 3 Engines with Cucumber & Rspec?

Question

I apologize if this question is slightly subjective... I am trying to figure out the best way to test Rails 3 Engines with Cucumber & Rspec. In order to test the engine a rails 3 app is necessary. Here is what I am currently doing:

1. Add a rails test app to the root of the gem (myengine) by running: rails new /myengine/rails_app

2. Add Cucumber to /myengine/rails_app/features as you would in a normal Rails app

3. Require the Rails Engine Gem (using :path=>"/myengine") in /myengine/rails_app/Gemfile

4. Add spec to the root directory of the gem: /myengine/spec

5. Include the fixtures in /myengine/spec/fixtures and I add the following to my cuc env.rb:

env.rb:

Fixtures.reset_cache
fixtures_folder = File.join(Rails.root, 'spec', 'fixtures')  
fixtures = Dir[File.join(fixtures_folder, '*.yml')].map {|f| File.basename(f, '.yml') }  
Fixtures.create_fixtures(fixtures_folder, fixtures)

Do you see any problems with setting it up like this? The tests run fine, but I am a bit hesitant to put the features inside the test rails app. I originally tried putting the features in the root of the gem and I created the test rails app inside features/support, but for some reason my engine would not initialize when I ran the tests, even though I could see the app loading everything else when cuc ran.

If anyone is working with Rails Engines and is using cuc and rspec for testing, I would be interested to hear your setup.

**UPDATE
I changed my setup a bit since I wrote this question. I decided to get rid of the spec directory under the root of the engine. Now I just create a rails app named "test_app" and setup cuc and rspec inside that app like I would normally do in a rails app. Then I include the gem like I did in step #3 above. Since the engine is a sub-app, I guess its just best to test it like it was a normal rails app. I am still interested in hearing if anyone has a different setup.

Answer 1

Rails 3.1 (will) generate a pretty good scaffold for engines. I'd recommend using RVM to create a new gemset called edge and switch to it:

rvm gemset create edge
rvm use @edge

Then install edge rails:

git clone git://github.com/rails/rails.git
cd rails
rake install

From there, you can follow Piotr Sarnacki's mountable app tutorial, replacing calls such as:

bundle exec ./bin/rails plugin new ../blog --edge --mountable

With simply:

rails plugin new blog --mountable --full

The mountable option makes the application mountable, whilst the full option makes it an engine with tests already built-in. To test the engine, this generator generates a folder in test called dummy which contains a small Rails application. You can see how this is loaded in test/test_helper.rb.

Then it's up to you to massage the data to do what it needs to in order to work. I would recommend copying over the cucumber files from a standard rails g cucumber:install into the project and then messing about with it until it works. I've done this once before so I know it's possible, but I cannot find the code right now.

Let me know how you go.

Answer 2

I'll explain how I did it using as example the following gem: https://github.com/skozlov/netzke-core

The testing application. It is in netzke-core/test/rails_app. This app can be run independently, so I can also use it for manual testing or for playing around with new features if I like.

In order for the testing app to load the gem itself, I have the following in application.rb:

$:.unshift File.expand_path('../../../../lib', __FILE__)
require 'netzke-core'

Cucumber features. They are in netzke-core/features. In env.rb I have:

require File.expand_path(File.dirname(__FILE__) + '/../../test/rails_app/config/environment')

... which will load the testing application before executing the features.

Specs. These are in netzke-core/spec. In spec_helper.rb I have the following:

require File.expand_path("../../test/rails_app/config/environment", __FILE__)

... which will load the testing application before running the specs.

Running tests. This setup lets me run the tests from the root of the gem:

cucumber features

and

rspec spec

Factory Girl. Not for this particular gem, but I'm normally using factory_girl instead of fixtures (see, for example, a similar setup in https://github.com/skozlov/netzke-basepack).