Setup RSpec to test a gem (not Rails)

Question

It is pretty easy with the added generator of rspec-rails to setup RSpec for testing a Rails application. But how about adding RSpec for testing a gem in development? I am not using jeweler or such tools. I just used Bundler (bundle gem my_gem) to setup the structure for the new gem and edit the *.gemspec manually. I also added s.add_development_dependency "rspec", ">= 2.0.0" to gemspec and did a bundle install.

Is there some nice tutorial what to do next to get RSpec working?

Answer 1

I've updated this answer to match current best practices:

Bundler supports gem development perfectly. If you are creating a gem, the only thing you need to have in your Gemfile is the following:

source "https://rubygems.org"
gemspec

This tells Bundler to look inside your gemspec file for the dependencies when you run bundle install.

Next up, make sure that RSpec is a development dependency of your gem. Edit the gemspec so it reads:

spec.add_development_dependency "rspec"

Next, create spec/spec_helper.rb and add something like:

require 'bundler/setup'
Bundler.setup

require 'your_gem_name' # and any other gems you need

RSpec.configure do |config|
  # some (optional) config here
end

The first two lines tell Bundler to load only the gems inside your gemspec. When you install your own gem on your own machine, this will force your specs to use your current code, not the version you have installed separately.

Create a spec, for example spec/foobar_spec.rb:

require 'spec_helper'
describe Foobar do
  pending "write it"
end

Optional: add a .rspec file for default options and put it in your gem's root path:

--color
--format documentation

Finally: run the specs:

$ rspec spec/foobar_spec.rb