Add end-to-end (system) tests (#25461)

config/application.rb

@@ -199,7 +199,7 @@ module Mastodon
     # We use our own middleware for this
     config.public_file_server.enabled = false
 
-    config.middleware.use PublicFileServerMiddleware if Rails.env.development? || ENV['RAILS_SERVE_STATIC_FILES'] == 'true'
+    config.middleware.use PublicFileServerMiddleware if Rails.env.development? || Rails.env.test? || ENV['RAILS_SERVE_STATIC_FILES'] == 'true'
     config.middleware.use Rack::Attack
     config.middleware.use Mastodon::RackMiddleware
 

config/webpack/tests.js

@@ -5,5 +5,5 @@ const { merge } = require('webpack-merge');
 const sharedConfig = require('./shared');
 
 module.exports = merge(sharedConfig, {
-  mode: 'development',
+  mode: 'production',
 });