Revert "Proxy webpack dev server in test environment"

This reverts commit 7afca793.

app/helpers/webpack_helper.rb

@@ -83,8 +83,16 @@ def webpack_entrypoint_paths(source, extension: nil, exclude_duplicates: true)
   end
 
   def webpack_public_host
-    # We proxy webpack output in 'test' and 'dev' environment, so we can just use asset_host
-    ActionController::Base.asset_host.try(:chomp, '/')
+    # We do not proxy the webpack output in the 'test' environment,
+    # so we must reference the webpack dev server directly.
+    if Rails.env.test? && Gitlab.config.webpack.dev_server.enabled
+      host = Gitlab.config.webpack.dev_server.host
+      port = Gitlab.config.webpack.dev_server.port
+      protocol = Gitlab.config.webpack.dev_server.https ? 'https' : 'http'
+      "#{protocol}://#{host}:#{port}"
+    else
+      ActionController::Base.asset_host.try(:chomp, '/')
+    end
   end
 
   def webpack_public_path

config/initializers/static_files.rb

@@ -21,7 +21,7 @@
 
   # If webpack-dev-server is configured, proxy webpack's public directory
   # instead of looking for static assets
-  if Gitlab.config.webpack.dev_server.enabled && Gitlab.dev_or_test_env?
+  if Gitlab.config.webpack.dev_server.enabled && Rails.env.development?
     app.config.middleware.insert_before(
       Gitlab::Middleware::Static,
       Gitlab::Webpack::DevServerMiddleware,