Add force_login option to OAuth authorize page (#8655)

* Add force_login option to OAuth authorize page

For when a user needs to sign into an app from multiple accounts
on the same server

* When logging out from modal header, redirect back after re-login

spec/controllers/oauth/authorizations_controller_spec.rb

@@ -5,23 +5,25 @@ require 'rails_helper'
 RSpec.describe Oauth::AuthorizationsController, type: :controller do
   render_views
 
-  let(:app) { Doorkeeper::Application.create!(name: 'test', redirect_uri: 'http://localhost/') }
+  let(:app) { Doorkeeper::Application.create!(name: 'test', redirect_uri: 'http://localhost/', scopes: 'read') }
 
   describe 'GET #new' do
     subject do
-      get :new, params: { client_id: app.uid, response_type: 'code', redirect_uri: 'http://localhost/' }
+      get :new, params: { client_id: app.uid, response_type: 'code', redirect_uri: 'http://localhost/', scope: 'read' }
     end
 
     shared_examples 'stores location for user' do
       it 'stores location for user' do
         subject
-        expect(controller.stored_location_for(:user)).to eq "/oauth/authorize?client_id=#{app.uid}&redirect_uri=http%3A%2F%2Flocalhost%2F&response_type=code"
+        expect(controller.stored_location_for(:user)).to eq "/oauth/authorize?client_id=#{app.uid}&redirect_uri=http%3A%2F%2Flocalhost%2F&response_type=code&scope=read"
       end
     end
 
     context 'when signed in' do
+      let!(:user) { Fabricate(:user) }
+
       before do
-        sign_in Fabricate(:user), scope: :user
+        sign_in user, scope: :user
       end
 
       it 'returns http success' do
@@ -35,6 +37,28 @@ RSpec.describe Oauth::AuthorizationsController, type: :controller do
       end
 
       include_examples 'stores location for user'
+
+      context 'when app is already authorized' do
+        before do
+          Doorkeeper::AccessToken.find_or_create_for(
+            app,
+            user.id,
+            app.scopes,
+            Doorkeeper.configuration.access_token_expires_in,
+            Doorkeeper.configuration.refresh_token_enabled?
+          )
+        end
+
+        it 'redirects to callback' do
+          subject
+          expect(response).to redirect_to(/\A#{app.redirect_uri}/)
+        end
+
+        it 'does not redirect to callback with force_login=true' do
+          get :new, params: { client_id: app.uid, response_type: 'code', redirect_uri: 'http://localhost/', scope: 'read', force_login: 'true' }
+          expect(response.body).to match(/Authorize/)
+        end
+      end
     end
 
     context 'when not signed in' do