Testing Rails Engine plugins with Rails 3

rubyonrails-core
1

Does anybody have any ideas for how to test a Rails Engine plugin with Rails 3?

To test a Rails Engine plugin, you have to embed a full Rails application inside of the plugin's test folder. There are a couple of old tricks for loading the plugin into the embedded Rails app, for testing: Testing Rails Engine Gems – Justin Ball Those tricks don't work any more with Rails 3, and the config.plugin_paths setting has been refactored away.

I've been looking at some of the more prominent Rails Engine plugins, like Clearance, Devise, etc. I haven't been able to find any examples of an embedded Rails 3 app for testing, even in the Rails 3 branch for Clearance.

2

Does anybody have any ideas for how to test a Rails Engine plugin with

Rails 3?

To test a Rails Engine plugin, you have to embed a full Rails

application inside of the plugin’s test folder. There are a couple of

old tricks for loading the plugin into the embedded Rails app, for

testing: http://www.justinball.com/2009/06/16/testing-rails-engine-gems/

Those tricks don’t work any more with Rails 3, and the

config.plugin_paths setting has been refactored away.

I’ve been looking at some of the more prominent Rails Engine plugins,

like Clearance, Devise, etc. I haven’t been able to find any examples

of an embedded Rails 3 app for testing, even in the Rails 3 branch for

Clearance.

Rails 3 branch for clearance is work-in-progress as it depends upon several other gems like formtastic. Inside your test/ directory create a rails_root which is a symlink to a rails3 application. Does that not work?

Anuj

3

Hello Anuj, thank you for your help.

My problem is: how do I get the Rails app that's in test/rails_root to load the plugin? The Rails app is inside of the plugin, rather than the plugin being inside of the Rails app like normal. test/rails_root/ vendor/plugins is empty so it doesn't load any plugins.

I have seen a couple of different references to ways to provide Rails with an alternate plugin loading path, but the one that appears to be 'most correct' and least hackish is the config.plugin_paths setting which was refactored out of Rails, here: http://github.com/rails/rails/commit/82b9b151ffde44305d67744c0bfd9bb5505f6fbe

Rails::Plugin::Locator has also been factored out of Rails, so overriding it and adding to the list of plugin_locators is no longer possible.

4

I'm not content with the current testing strategy for Clearance. It has served us well for the 2.x series of Rails but not for Rails 3 while maintaining backwards compatibility.

The most extensive backwards Rails compatibility testing of a library I've seen is in Hoptoad Notifier:

http://github.com/thoughtbot/hoptoad_notifier/blob/master/features/step_definitions/rails_application_steps.rb

That allows us to support a pretty good range of versions of Rails:

http://github.com/thoughtbot/hoptoad_notifier/blob/master/SUPPORTED_RAILS_VERSIONS

I'd like to see this extracted into it's own library for testing your library for backwards Rails compatibility. It also needs to be extended to work with Rails 3.

5

Not sure if this helps you, but I'm treating all my engine plugins as standalone rails applications. What this means is each engine plugin is theoretically able to run as a standalone application and can therefor be tested the same way as any other rails application. I think the overhead is acceptable and it has worked well for the past couple years.

Daniel

6

Hello Anuj, thank you for your help.

My problem is: how do I get the Rails app that’s in test/rails_root to load the plugin? The Rails app is inside of the plugin, rather than the plugin being inside of the Rails app like normal. test/rails_root/ vendor/plugins is empty so it doesn’t load any plugins.

Jose Valim seems to be creating a gem to test rails plugins: see

http://github.com/josevalim/enginex