Refactor preview environment loading

This allows us to load preview environments in the correct context:
e.g. on staging (where Rails.env.production? and !ENV['SERVE_TEST_UI'].blank?)
the preview should point to https://galc-api.ucblib.org/.

Routing is explicitly not enabled for the new preview controller/routes unless
there is a value for ENV['SERVE_TEST_UI'].

Author: anarchivist

Gemfile

@@ -36,6 +36,7 @@ end
 group :test do
   gem 'database_cleaner-active_record', '~> 2.0'
   gem 'factory_bot_rails'
+  gem 'rails-controller-testing'
   gem 'rspec', '~> 3.10'
   gem 'rspec_junit_formatter', '~> 0.5'
   gem 'rspec-rails', '~> 5.0'

Gemfile.lock

@@ -218,6 +218,10 @@ GEM
       activesupport (= 7.0.4.3)
       bundler (>= 1.15.0)
       railties (= 7.0.4.3)
+    rails-controller-testing (1.0.5)
+      actionpack (>= 5.0.1.rc1)
+      actionview (>= 5.0.1.rc1)
+      activesupport (>= 5.0.1.rc1)
     rails-dom-testing (2.0.3)
       activesupport (>= 4.2.0)
       nokogiri (>= 1.6)
@@ -347,6 +351,7 @@ DEPENDENCIES
   puma (~> 5.0)
   rack-cors
   rails (~> 7.0.4)
+  rails-controller-testing
   ransack (~> 2.6)
   rspec (~> 3.10)
   rspec-rails (~> 5.0)

app/controllers/auth_controller.rb

@@ -7,10 +7,7 @@ class AuthController < ApplicationController
   def index
     raise Error::NotFoundError if ENV['SERVE_TEST_UI'].blank?
 
-    # TODO: Something more elegant
-    # Hack to get around the fact that API-only apps don't include an HTML renderer
-    pathname = Rails.root.join('public', 'index.html')
-    render xml: File.read(pathname), content_type: 'text/html'
+    redirect_to preview_path
   end
 
   def callback

app/controllers/preview/application_controller.rb

@@ -0,0 +1,3 @@
+module Preview
+  class ApplicationController < ActionController::Base; end
+end

app/controllers/preview/preview_controller.rb

@@ -0,0 +1,8 @@
+module Preview
+  class PreviewController < Preview::ApplicationController
+
+    def index
+      @api_url = Rails.env.production? ? 'https://galc-api.ucblib.org' : 'http://localhost:3000'
+    end
+  end
+end

public/index.html renamed to app/views/preview/preview/index.html.erb

@@ -16,7 +16,7 @@
     <main>
         <div class="layout-content">
             <div class="region region-content">
-                <div id="galc-app" data-api-base-url="http://localhost:3000" class="block-views"></div>
+                <div id="galc-app" data-api-base-url="<%= @api_url %>" class="block-views"></div>
             </div>
         </div>
     </main>

config/routes.rb

@@ -5,6 +5,12 @@
   get '/logout', to: 'auth#logout', as: :logout
   get '/auth/:provider/callback', to: 'auth#callback', as: :omniauth_callback
 
+  scope module: 'preview' do
+    constraints(->(_) { ENV['SERVE_TEST_UI'].present? }) do
+      get '/preview', to: 'preview#index', as: :preview
+    end
+  end
+
   defaults format: :jsonapi do
     constraints(->(req) { req.format == :jsonapi }) do
       resources :closures

spec/requests/auth_spec.rb

@@ -46,12 +46,11 @@
       expect(response).to have_http_status(:not_found)
     end
 
-    it 'serves a test UI in staging' do
+    it 'redirects to a test UI in staging' do
       allow(ENV).to receive(:[]).with('SERVE_TEST_UI').and_return(true)
 
       get root_path
-      expect(response).to have_http_status(:ok)
-      expect(response.content_type).to start_with('text/html')
+      expect(response).to redirect_to(preview_path)
     end
   end
 

spec/requests/preview/preview_spec.rb

@@ -0,0 +1,30 @@
+require 'rails_helper'
+
+RSpec.describe Preview::PreviewController, type: :request do
+  describe 'GET /preview' do
+    context 'with the preview environment enabled' do
+      it 'shows a test UI in when SERVE_TEST_UI is true' do
+        allow(ENV).to receive(:[]).with('SERVE_TEST_UI').and_return(true)
+        get preview_path
+        expect(response).to have_http_status(:ok)
+        expect(response.content_type).to start_with('text/html')
+      end
+
+      context 'sets the API URL correctly' do
+        it 'sets the url for staging API in production' do
+          allow(ENV).to receive(:[]).with('SERVE_TEST_UI').and_return(true)
+          allow(Rails.env).to receive(:production?).and_return(true)
+          get preview_path
+          expect(assigns(:api_url)).to eq('https://galc-api.ucblib.org')
+        end
+
+        it 'sets the url for API to be localhost in dev/test' do
+          allow(ENV).to receive(:[]).with('SERVE_TEST_UI').and_return(true)
+          allow(Rails.env).to receive(:production?).and_return(false)
+          get preview_path
+          expect(assigns(:api_url)).to eq('http://localhost:3000')
+        end
+      end
+    end
+  end
+end

spec/routing/preview/preview_routing_spec.rb

@@ -0,0 +1,13 @@
+require 'rails_helper'
+
+RSpec.describe 'preview routing', type: :routing do
+  it 'is not routable with an empty SERVE_TEST_UI' do
+    allow(ENV).to receive(:[]).with('SERVE_TEST_UI').and_return(nil)
+    expect(get: preview_path).not_to be_routable
+  end
+
+  it 'routes to Preview::PreviewController when SERVE_TEST_UI is set' do
+    allow(ENV).to receive(:[]).with('SERVE_TEST_UI').and_return('something')
+    expect(get: preview_path).to route_to('preview/preview#index')
+  end
+end