Raising route not found error

Question

I'm writing a book on Rails 3 at the moment and past-me has written in Chapter 3 or so that when a specific feature is run that a routing error is generated. Now, it's unlike me to go writing things that aren't true, so I'm pretty sure this happened once in the past.

I haven't yet been able to duplicate the scenario myself, but I'm pretty confident it's one of the forgotten settings in the environment file.

To duplicate this issue:

• Generate a new rails project
• important: Remove the public/index.html file
• Add cucumber-rails and capybara to the "test" group in your Gemfile
• run bundle install
• run rails g cucumber:skeleton
• Generate a new feature, call it features/creating_projects.feature
• Inside this feature put:

This:

Feature: Creating projects
  In order to value
  As a role
  I want feature

Scenario: title
  Given I am on the homepage

When you run this feature using bundle exec cucumber features/creating_projects.feature it should fail with a "No route matches /" error, because you didn't define the root route. However, what I and others are seeing is that it doesn't.

Now I've set a setting in test.rb that will get this exception page to show, but I would rather Rails did a hard-raise of the exception so that it showed up in Cucumber as a failing step, like I'm pretty sure it used to, rather than a passing step.

Does anybody know what could have changed since May-ish of last year for Rails to not do this? I'm pretty confident it's some setting in config/environments/test.rb, but for the life of me I cannot figure it out.

Answer 1

After I investigate the Rails source code, it seems like the ActionDispatch::ShowExceptions middleware that responsible of raising exception ActionController::RoutingError is missing in the test environment. Confirmed by running rake middleware and rake middleware RAILS_ENV=test.

You can see that in https://github.com/josh/rack-mount/blob/master/lib/rack/mount/route_set.rb#L152 it's returning X-Cascade => 'pass' header, and it's ActionDispatch::ShowExceptions's responsibility to pick it up (in https://github.com/rails/rails/blob/master/actionpack/lib/action_dispatch/middleware/show_exceptions.rb#L52)

So the reason you're seeing that your test case is passing because rack-mount is returning "Not Found" text, with status 404.

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I'll git blame people and get it fix for you. It's this conditional here: https://github.com/rails/rails/blob/master/railties/lib/rails/application.rb#L159. If the setting is true, the error got translated right but we got error page output. If it's false, then this middleware doesn't get loaded at all. Hold on ...

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Update: To clearify the previous block, you're hitting the dead end here. If you're setting action_dispatch.show_exceptions to false, you'll not get that middleware loaded, resulted in the 404 error from rack-mount got rendered. Whereas if you're setting action_dispatch.show_exceptions to true, that middleware will got loaded but it will rescue the error and render a nice "exception" page for you.