Align project files with CodeHarbor

Since both projects are developed together and by the same team, we also want to have the same code structure and utility methods available in both projects. Therefore, this commit changes many files, but without a functional change.

spec/controllers/sessions_controller_spec.rb

@@ -2,14 +2,14 @@
 
 require 'rails_helper'
 
-describe SessionsController do
+RSpec.describe SessionsController do
   render_views
 
   let(:consumer) { create(:consumer) }
 
   describe 'POST #create' do
     let(:password) { attributes_for(:teacher)[:password] }
-    let(:user) { InternalUser.create(user_attributes.merge(password:)) }
+    let(:user) { InternalUser.create(user_attributes.merge(password:, consumer:)) }
     let(:user_attributes) { build(:teacher).attributes }
 
     context 'with valid credentials' do
@@ -76,7 +76,7 @@ describe SessionsController do
     context 'with valid launch parameters' do
       let(:locale) { :de }
       let(:perform_request) { post :create_through_lti, params: {custom_locale: locale, custom_token: exercise.token, oauth_consumer_key: consumer.oauth_key, oauth_nonce: nonce, oauth_signature: SecureRandom.hex, user_id: user.external_id} }
-      let(:user) { create(:external_user, consumer_id: consumer.id) }
+      let(:user) { create(:external_user, consumer:) }
 
       before { allow_any_instance_of(IMS::LTI::ToolProvider).to receive(:valid_request?).and_return(true) }