Rails Engine - Gems dependencies, how to load them into the application?

Question

I\'m doing an engine here, it works alright in stand alone.

When I transform it into a gem, and load it inside another application, I get a lot of undefined errors,

Answer 1

At the time being (Rails 3.1 and above I think), you shouldn't have do declare any gems in the test/dummy/Gemfile anymore:

Quote from test/dummy/Gemfile (generated using rails plugin new my_engine --full):

Declare your gem's dependencies in simple_view_helpers.gemspec. Bundler will treat runtime dependencies like base dependencies, and development dependencies will be added by default to the :development group.

Declare any dependencies that are still in development here instead of in your gemspec. These might include edge Rails or gems from your path or Git. Remember to move these dependencies to your gemspec before releasing your gem to rubygems.org.