instrumental/spec/controllers/auth/registrations_controller_spec.rb

require 'rails_helper'

RSpec.describe Auth::RegistrationsController, type: :controller do
  render_views

  describe 'GET #new' do
    before do
      Setting.open_registrations = true
      request.env["devise.mapping"] = Devise.mappings[:user]
    end

    it 'returns http success' do
      get :new
      expect(response).to have_http_status(:success)
    end
  end

  describe 'POST #create' do
    let(:accept_language) { Rails.application.config.i18n.available_locales.sample.to_s }

    before do
      Setting.open_registrations = true
      request.env["devise.mapping"] = Devise.mappings[:user]
      request.headers["Accept-Language"] = accept_language
      post :create, params: { user: { account_attributes: { username: 'test' }, email: 'test@example.com', password: '12345678', password_confirmation: '12345678' } }
    end

    it 'redirects to login page' do
      expect(response).to redirect_to new_user_session_path
    end

    it 'creates user' do
      user = User.find_by(email: 'test@example.com')
      expect(user).to_not be_nil
      expect(user.locale).to eq(accept_language)
    end
  end
end