Populate Instance Variable Defined In Parent Controller For Rspec Test

Question

In my ApplicationController, I expose a variable that can be shared by all controllers:

before_filter :expose_group

protected

    # Much simplified
    def expose_group
      @user_group = LearningGroup.find_by_uid(cookies[:user_group])
    end

I'm testing my controllers using RSpec, and for some of these tests, I need to be able to set the @user_group to a known value before they are run. How can I set this variable when testing a subclass of ApplicationController?

Note: I need a way to set @user_group for the test. Controlling the return value of expose_group using a stub doesn't help as @user_group will still be nil.

James · Accepted Answer · 2013-08-26 14:07:54Z

I would scrap the instance variable altogether and use helpers instead. Start with something like a GroupsHelper in app/helpers/groups_helper.rb.

module GroupsHelper
  def user_group
    @user_group ||= group_from_cookie
  end

  def user_group=(group)
    @user_group = group
  end

  private

  def group_from_cookie
    group_uid = cookies[:user_group]
    LearningGroup.find_by_uid group_uid unless group_uid.nil?
  end
end

Then include it in ApplicationController.

class ApplicationController < ActionController::Base
  include GroupsHelper
  # ...
end

Now, in spec/support define a helper for your test.

include ApplicationHelper

def join_group group_uid
  # whatever preparation you may need to do as well
  cookies[:user_group] = group_uid
end

A test could look something like:

it 'does something awesome' do
  join_group 'my awesome group id'
  # ...
  expect(your_subject).to be_awesome
end

When you run your test, user_group will return the value determined by the value you already assigned to the cookie object.

This also has the benefit of just calling join_group rather than stubbing LearningGroup all over the place in multiple tests.

apneadiving · Accepted Answer · 2013-08-26 13:44:45Z

1

I'd simply stub the method like:

LearningGroup.should_receive(:find_by_uid).and_return known_value

answered Aug 26, 2013 at 13:44

apneadiving

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5 Comments

Undistraction Over a year ago

This would only allow me to control the return value of expose_group, but what I need is a way to populate the @leaning_group instance variable.

apneadiving Over a year ago

where is this variable defined?

Undistraction Over a year ago

It's defined right there in the expose_group method. It's defined there in the ApplicationController and used in the subclass that I'm testing.

apneadiving Over a year ago

you define @user_group there. the variable will be set with your known value if the before filter is executed. If it's not the should_receive will let you know

Undistraction Over a year ago

Sorry. I've got you. Thanks.

ventsislaf · Accepted Answer · 2013-08-26 13:42:43Z

0

You can stub expose_group method to return what you want.

In your specs:

controller.stub(expose_group: 'what you need')

answered Aug 26, 2013 at 13:42

ventsislaf

1,67112 silver badges21 bronze badges

2 Comments

Undistraction Over a year ago

But it's only returning anything implicitly. It's not the return value of expose_group that I need to control, but the instance variable.

ventsislaf Over a year ago

In this case the answer of @apneadiving is what you need.

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