Trying to test your gems in the context of a test Rails application is hard. This gem makes it easy.
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Testing Rails gem plugins using cucumber can be difficult since gems need to be tested in the context of a host Rails application, which isn't part of your gem. Cukigem gives you cucumber steps to make testing your gem in the context of a Rails application easy.

This is a nice addition to gems as it's more of an integration test - verifying that your gem actually works and is successfully-installed in a Rails application via the Gemfile.

This is not a gem but a collection of useful steps. Simply copy the step definition files located in step_definitions, and the support files located in support, into your own project.


See this example in use on my message_block project. All of the step definitions should be self-explanatory if you read the step_definitions/cukigem_steps.rb file.

Feature: Message Block
  Scenario: Installing Static Files
    Given I have a rails application
    And I run "rake message_block:install --trace"
    Then the file "public/images/message_block" should exist
    And the file "public/stylesheets/message_block.css" should exist
    And the file "public/javascripts/message_block.js" should exist

  Scenario: Displaying Model Errors mixed with Flash Messages
    Given I have a rails application
    And I run "rails g scaffold model name:string"
    And I setup the database
    And I save the following as "app/controllers/models_controller.rb":
    class ModelsController < ApplicationController
      def index
        @model =
        @model.errors.add(:base, "Model-One")
        @model.errors.add(:base, "Model-Two")[:error] = "Controller-One"[:confirm] = "Controller-Two"
    And I save the following as "app/views/models/index.html.erb":
    <%= message_block :on => :model %>
    And I start the rails application
    When I go to the models page
    Then I should see "Model-One"
    And I should see "Model-Two"
    And I should see "Controller-One"
    And I should see "Controller-Two"

Known Issues

  • Be careful when using multiple “generate a rails application” steps in one test run. The problem is that we can only require the config/environment.rb file once, so if you blow away and generate a new application in the course of the test run, things will not behave as expected. Cukigem does a lot to “reset” your app to a blank state so there should rarely be a need to fully generate a new application except if one doesn't already exist.


I am really looking for contributions here. I created this after looking for a standard way of testing my gems using cucumber and I was unable to find anything (except for some nice code in the paperclip project which did most of what I needed). Patches/pull-requests welcome.


Thanks to Jon Yurek of Thoughtbot for getting me thinking about this after seeing his work on Rails app generation and cucumber within the paperclip project.