Testing Rails with request specs, instance variables and custom primary keys

Question

I'm attempting to write a request spec for a Rails app in API-only mode. In the UsersController, a before_action sets the @user using @uid (the primary key), which I'm attempting to assign in the spec.

User.uid is a custom primary key, User.find() works fine in development and production (as does everything else, I'm trying to learn how to test here). This is the error I receive in test:

Failure/Error @user = User.find(@uid)
 ActiveRecord::RecordNotFound:
 Couldn't find User without an ID

//controller
module Api
  module V1
    class UsersController < ApplicationController
      before_action :set_user, only: %i[show update]

      def show
        render json: @user
      end
    private
      def set_user
        @user = User.find(@uid)
      end
   end
end
// request spec
require 'rails_helper'
require 'test_helper'

describe 'get user route' do
  let!(:user) { FactoryBot.create(:user) }
  before :each do
    allow_any_instance_of(ApplicationController).to receive(:authorize).and_return(true)
    @uid = user.uid
  end
  
  before { get '/api/v1/user' }

  it 'returns status code 200' do
    expect(response).to have_http_status(:success)
  end
end

"authorize" is a before action on the ApplicationController that assigns @uid. I'm skipping it and trying to assign @uid to the created user's uid. There must be a better way to do this as well...

edit: I'm using Ruby 2.7.1 and the rspec-rails gem 4.0.1

The @uid is being set with a method in the ApplicationController which is used as a before_action. It's using a library to decode a firebase jwt and return an auth_user object which contains the uid.

class ApplicationController < ActionController::API
  def authorize
    auth_user = FirebaseIdToken::Signature.verify(params[:idToken])
    @uid = auth_user ? auth_user['user_id'] : nil
    render json: {}, status: 401 if @uid.nil?
  end
end

I've read some posts that say that you lose the ability to set the instance variables by using a request spec (can't find this in the docs), because these types of specs are supposed to mimic a real scenario as much as possible. The controller instance variable is only available after the request so I'm not sure if it's possible at all to assign a controller's instance variable from a request spec.

Sampat Badhe · Accepted Answer · 2020-10-08 15:36:11Z

1

The way you have set @uid in spec, will not be available in controller. you need to set instance variable as follow be accessible in controller.

controller.instance_variable_set(:@uid, user.uid)

require 'rails_helper'
require 'test_helper'

describe 'get user route' do
  let!(:user) { FactoryBot.create(:user) }
  before :each do
    allow_any_instance_of(ApplicationController).to receive(:authorize).and_return(true)
    controller.instance_variable_set(:@uid, user.uid)
  end
  
  before { get '/api/v1/user' }

  it 'returns status code 200' do
    expect(response).to have_http_status(:success)
  end
end

edited Oct 8, 2020 at 15:36

answered Oct 8, 2020 at 6:13

Sampat Badhe

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6 Comments

Meursault Over a year ago

using this approach I get the following error: NameError: `uid' is not allowed as an instance variable name

Meursault Over a year ago

with controller.instance_variable_set(:@uid, user.uid) the error is FrozenError: can't modify frozen NilClass: nil

Sampat Badhe Over a year ago

Which ruby and rspec version you are using? also could you please provide the snippet where you are setting @uid?

Meursault Over a year ago

I answered your questions by editing the question. I appreciate your help but I'm not sure this is possible

Sampat Badhe Over a year ago

@Meursault have you tried the steps given in firebase_id_token Gem for specs? - github.com/fschuindt/firebase_id_token#rails-test

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