Clarify dev_server.running? first checks configured

Webpacker.dev_server.running? might appear to be costly, but it first
checks that the dev_server value is on the config Hash.

Renaming the method makes it clear that the first check is whether it is
configured.

Since the dev_server would ever be configured on production, there is no
cost for calling this method on production.

CHANGELOG.md

@@ -26,8 +26,9 @@ environment.loaders.append('nodeModules', nodeModules)
 - Simple webpack config
 - Removed integration installers
 - Splitchunks enabled by default
-- CSS extraction enabled by default
+- CSS extraction enabled by default, except when devServer is configured and running
 - Optional CSS support
+- Renamed DevServer.running? to DevServer.configured_and_running?
 
 ## [[5.4.0]](https://github.com/rails/webpacker/compare/v5.3.0...v5.4.0) - 2021-05-18
 

lib/webpacker/dev_server.rb

@@ -11,7 +11,7 @@ def initialize(config)
     @config = config
   end
 
-  def running?
+  def configured_and_running?
     if config.dev_server.present?
       Socket.tcp(host, port, connect_timeout: connect_timeout).close
       true

lib/webpacker/dev_server_proxy.rb

@@ -10,7 +10,7 @@ def initialize(app = nil, opts = {})
   end
 
   def perform_request(env)
-    if env["PATH_INFO"].start_with?("/#{public_output_uri_path}") && dev_server.running?
+    if env["PATH_INFO"].start_with?("/#{public_output_uri_path}") && dev_server.configured_and_running?
       env["HTTP_HOST"] = env["HTTP_X_FORWARDED_HOST"] = dev_server.host
       env["HTTP_X_FORWARDED_SERVER"] = dev_server.host_with_port
       env["HTTP_PORT"] = env["HTTP_X_FORWARDED_PORT"] = dev_server.port.to_s

lib/webpacker/helper.rb

@@ -128,6 +128,10 @@ def preload_pack_asset(name, **options)
   #   <link rel="stylesheet" media="screen" href="/packs/calendar-8c7ce31a.chunk.css" />
   #   <link rel="stylesheet" media="screen" href="/packs/map-8c7ce31a.chunk.css" />
   #
+  #   When using the webpack-dev-server, CSS is inlined so HMR can be turned on for CSS,
+  #   including CSS modules
+  #   <%= stylesheet_pack_tag 'calendar', 'map' %> # => nil
+  #
   # DO:
   #
   #   <%= stylesheet_pack_tag 'calendar', 'map' %>
@@ -137,7 +141,8 @@ def preload_pack_asset(name, **options)
   #   <%= stylesheet_pack_tag 'calendar' %>
   #   <%= stylesheet_pack_tag 'map' %>
   def stylesheet_pack_tag(*names, **options)
-    unless current_webpacker_instance.dev_server.running?
+    css_extracted = !Webpacker.dev_server.configured_and_running?
+    if css_extracted
       stylesheet_link_tag(*sources_from_manifest_entrypoints(names, type: :stylesheet), **options)
     end
   end

lib/webpacker/manifest.rb

@@ -51,7 +51,7 @@ def lookup!(name, pack_type = {})
 
   private
     def compiling?
-      config.compile? && !dev_server.running?
+      config.compile? && !dev_server.configured_and_running?
     end
 
     def compile

lib/webpacker/railtie.rb

@@ -8,7 +8,7 @@ class Webpacker::Engine < ::Rails::Engine
   config.webpacker = ActiveSupport::OrderedOptions.new
 
   initializer "webpacker.proxy" do |app|
-    insert_middleware = Webpacker.config.dev_server.present? rescue nil
+    insert_middleware = Webpacker.config.dev_server.present?
     if insert_middleware
       app.middleware.insert_before 0,
         Rails::VERSION::MAJOR >= 5 ?

test/dev_server_test.rb

@@ -2,7 +2,7 @@
 
 class DevServerTest < Webpacker::Test
   def test_running?
-    refute Webpacker.dev_server.running?
+    refute Webpacker.dev_server.configured_and_running?
   end
 
   def test_host