How to use assigns() in a Rails request spec without a dependency

Several years ago, the Rails core team advised that controller tests/specs were being discouraged, in favour of request specs. The basis for this was that controller tests had more visibility into the internals of the controller, and were not purely testing the HTTP interaction as request specs were.

This is valid, but one method I end up missing a lot from controller specs is assigns - as in (expect(assigns(:widget)).to be_published). While the assertions available to controller tests are easily installable as a gem, getting the assigns method back is super simple.

It’s pretty common to put support modules into place - for example, in spec|test/support/request_spec_helpers.rb:

module RequestSpecHelpers
  def assigns(key)
    controller.view_assigns.fetch(key.to_s)
  end
end

In Test::Unit, this can just be included into your ActionDispatch::IntegrationTest:

class WidgetRequestTest < ActionDispatch::IntegrationTest
  include RequestSpecHelpers
end

And in RSpec, it can be included with config:

RSpec.configure do |config|
  config.include RequestSpecHelpers, type: :request
end