Address review

1. hmr default is false
2. CSS is extracted unless yml file configuredd HMR and running webpack-dev-server

lib/install/config/webpacker.yml

@@ -26,7 +26,7 @@ development:
     port: 3035
     public: localhost:3035
     # Hot Module Replacement updates modules while the application is running without a full reload
-    hmr: true
+    hmr: false
     # Should we show a full-screen overlay in the browser when there are compiler errors or warnings?
     overlay: true
     # Should we use gzip compression?

lib/webpacker/dev_server.rb

@@ -61,6 +61,8 @@ def env_prefix
 
   private
     def fetch(key)
+      return nil unless config.dev_server.present?
+
       ENV["#{env_prefix}_#{key.upcase}"] || config.dev_server.fetch(key, defaults[key])
     end
 

lib/webpacker/dev_server_runner.rb

@@ -74,13 +74,15 @@ def execute_cmd
         end
 
         if @argv.include?("--debug-webpacker")
-          cmd = [ "node", "--inspect-brk"] + cmd
+          cmd = [ "node", "--inspect-brk", "--trace-warnings" ] + cmd
           @argv.delete "--debug-webpacker"
         end
 
         cmd += ["--config", @webpack_config]
         cmd += ["--progress", "--color"] if @pretty
-        cmd += ["--hot"] if @hot
+
+        # Something about webpack config makes this always mandatory
+        cmd += ["--hot"]
         cmd += @argv
 
         Dir.chdir(@app_path) do

lib/webpacker/helper.rb

@@ -141,10 +141,10 @@ def preload_pack_asset(name, **options)
   #   <%= stylesheet_pack_tag 'calendar' %>
   #   <%= stylesheet_pack_tag 'map' %>
   def stylesheet_pack_tag(*names, **options)
-    css_extracted = !Webpacker.dev_server.configured_and_running?
-    if css_extracted
-      stylesheet_link_tag(*sources_from_manifest_entrypoints(names, type: :stylesheet), **options)
-    end
+    css_inline = Webpacker.dev_server.hmr? && Webpacker.dev_server.configured_and_running?
+    return "" if css_inline
+
+    stylesheet_link_tag(*sources_from_manifest_entrypoints(names, type: :stylesheet), **options)
   end
 
   private

package/utils/get_style_rule.js

@@ -1,5 +1,6 @@
 /* eslint global-require: 0 */
 
+const devServer = require('../dev_server')
 const { canProcess, moduleExists, runningWebpackDevServer } = require('./helpers')
 
 const getStyleRule = (test, preprocessors = []) => {
@@ -10,9 +11,11 @@ const getStyleRule = (test, preprocessors = []) => {
         options: { sourceMap: true }
       }))
 
+    // style-loader is required when using css modules with HMR on the webpack-dev-server
+    const cssInline = runningWebpackDevServer && devServer.hmr
+
     const use = [
-      // style-loader is required when using css modules with HMR, so just always use for the dev-server
-      runningWebpackDevServer ? 'style-loader' : require('mini-css-extract-plugin').loader,
+      cssInline ? 'style-loader' : require('mini-css-extract-plugin').loader,
       {
         loader: require.resolve('css-loader'),
         options: {

test/dev_server_runner_test.rb

@@ -13,25 +13,25 @@ def teardown
   end
 
   def test_run_cmd_via_node_modules
-    cmd = ["#{test_app_path}/node_modules/.bin/webpack", "serve", "--config", "#{test_app_path}/config/webpack/development.js"]
+    cmd = ["#{test_app_path}/node_modules/.bin/webpack", "serve", "--config", "#{test_app_path}/config/webpack/development.js", "--hot"]
 
     verify_command(cmd, use_node_modules: true)
   end
 
   def test_run_cmd_via_yarn
-    cmd = ["yarn", "webpack", "serve", "--config", "#{test_app_path}/config/webpack/development.js"]
+    cmd = ["yarn", "webpack", "serve", "--config", "#{test_app_path}/config/webpack/development.js", "--hot"]
 
     verify_command(cmd, use_node_modules: false)
   end
 
   def test_run_cmd_argv
-    cmd = ["#{test_app_path}/node_modules/.bin/webpack", "serve", "--config", "#{test_app_path}/config/webpack/development.js", "--quiet"]
+    cmd = ["#{test_app_path}/node_modules/.bin/webpack", "serve", "--config", "#{test_app_path}/config/webpack/development.js", "--hot", "--quiet"]
 
     verify_command(cmd, argv: ["--quiet"])
   end
 
   def test_run_cmd_argv_with_https
-    cmd = ["#{test_app_path}/node_modules/.bin/webpack", "serve", "--config", "#{test_app_path}/config/webpack/development.js", "--https"]
+    cmd = ["#{test_app_path}/node_modules/.bin/webpack", "serve", "--config", "#{test_app_path}/config/webpack/development.js", "--hot", "--https"]
 
     dev_server = Webpacker::DevServer.new({})
     def dev_server.host; "localhost"; end
@@ -45,7 +45,7 @@ def dev_server.hmr?; false; end
   end
 
   def test_environment_variables
-    cmd = ["#{test_app_path}/node_modules/.bin/webpack", "serve", "--config", "#{test_app_path}/config/webpack/development.js"]
+    cmd = ["#{test_app_path}/node_modules/.bin/webpack", "serve", "--config", "#{test_app_path}/config/webpack/development.js", "--hot" ]
     env = Webpacker::Compiler.env.dup
     env["WEBPACKER_CONFIG"] = "#{test_app_path}/config/webpacker.yml"
     env["WEBPACK_DEV_SERVER"] = "true"