How do you test a Rails controller method exposed as a helper_method?

Question

They don\'t seem to be accessible from ActionView::TestCase

Answer 1

You could test @controller.view_context from your functional/controller tests. This method is available in Rails 3, 4, and 5, as far as I can tell.

app/controllers/application_controller.rb

class ApplicationController < ActionController::Base
  helper_method :current_user
  # ...
end

test/controllers/application_controller_test.rb

require 'test_helper'

class ApplicationControllerTest < ActionController::TestCase
  test 'current_user helper exists in view context' do
    assert_respond_to @controller.view_context, :current_user
  end
end

If you didn't want to test one of your controller subclasses, you could also create a test controller to verify that the method in the view_context is the same one from the controller and not from one of your view helpers.

class ApplicationControllerHelperTest < ActionController::TestCase
  class TestController < ApplicationController
    private
    def current_user
      User.new
    end
  end

  tests TestController

  test 'current_user helper exists in view context' do
    assert_respond_to @controller.view_context, :current_user
  end

  test 'current_user returns value from controller' do
    assert_instance_of User, @controller.view_context.current_user
  end
end

Or, more likely, you'd want to be able to test the helper in the presence of a request.

class ApplicationControllerHelperTest < ActionController::TestCase
  class TestController < ApplicationController
    def index
      render plain: 'Hello, World!'
    end
  end

  tests TestController

  def with_routing
    # http://api.rubyonrails.org/classes/ActionDispatch/Assertions/RoutingAssertions.html#method-i-with_routing
    # http://guides.rubyonrails.org/routing.html#connecting-urls-to-code
    super do |set|
      set.draw do
        get 'application_controller_test/test', to: 'application_controller_test/test#index'
      end

      yield
    end
  end

  test 'current_user helper exists in view context' do
    assert_respond_to @controller.view_context, :current_user
  end

  test 'current_user returns value from controller' do
    with_routing do
      # set up your session, perhaps
      user = User.create! username: 'testuser'
      session[:user_id] = user.id

      get :index
      assert_equal user.id, @controller.view_context.current_user.id
    end
  end
end