Temporarily patch the Rails configuration for the duration of a block

gistfile1.rb

# Temporarily patch the Rails configuration for the duration of a block.
# For example:
#
#   test "should create a resque job when background_jobs is true" do
#     with_config :background_jobs=>true do
#       repo = Repo.create :url=>TEST_CLONE_URL
#       assert_queued(CloneJob, [repo.pk])
#     end
#   end
#
def with_config(opts)
  old_config = {}

  opts.each do |key, value|
    old_config[key] = Rails.configuration.send(key)
    Rails.configuration.send("#{key}=", value)
  end

  begin
    yield

  ensure
    old_config.each do |key, value|
      Rails.configuration.send("#{key}=", value)
    end
  end
end