Support server-rendering from webpack-dev-server

.travis.yml

@@ -10,14 +10,16 @@ rvm:
   - jruby-9.0.1.0
 
 gemfile:
+  # These have webpacker:
+  - gemfiles/rails_4.2_sprockets_4.gemfile
+  - gemfiles/rails_5_no_sprockets_webpacker.gemfile
+  # These don't have webpacker:
   - gemfiles/rails_3.2.gemfile
   - gemfiles/rails_4.0.5.gemfile
   - gemfiles/rails_4.0_with_therubyracer.gemfile
   - gemfiles/rails_4.1.gemfile
   - gemfiles/rails_4.2_sprockets_2.gemfile
   - gemfiles/rails_4.2_sprockets_3.gemfile
-  - gemfiles/rails_4.2_sprockets_4.gemfile
-  - gemfiles/rails_5_no_sprockets_webpacker.gemfile
   - gemfiles/rails_5_no_sprockets.gemfile
   - gemfiles/rails_5_sprockets_4.gemfile
 

lib/react/server_rendering/webpacker_manifest_container.rb

@@ -2,13 +2,17 @@
 
 module React
   module ServerRendering
+    CLIENT_REQUIRE = %r{__webpack_require__\(.*webpack-dev-server\/client\/index\.js.*\n}
+
     # Get a compiled file from Webpacker
     class WebpackerManifestContainer
       def find_asset(logical_path)
         asset_path = Webpacker::Manifest.lookup(logical_path) # raises if not found
         if asset_path.start_with?("http")
-          # TODO: this includes webpack-dev-server code which causes ExecJS to 💥
+          # this includes `webpack-dev-server/client/index.js` code which causes ExecJS to 💥
           dev_server_asset = open(asset_path).read
+          dev_server_asset.sub!(CLIENT_REQUIRE, '//\0')
+          dev_server_asset
         else
           full_path = File.join(
             # TODO: using `.parent` here won't work for nonstandard configurations

test/dummy/app/javascript/components/GreetingMessage.js

@@ -16,7 +16,7 @@ module.exports = React.createClass({
   },
   render: function() {
     return React.DOM.div({},
-      React.DOM.div({}, this.state.greeting, ' ', this.props.name),
+      React.DOM.div({}, this.state.greeting, ' from Webpacker ', this.props.name ),
       React.DOM.button({onClick: this.goodbye}, 'Goodbye')
     );
   }

test/react/rails/pages_controller_test.rb

@@ -25,4 +25,15 @@ class PagesControllerTest < ActionController::TestCase
       assert_includes(response.body, "Hello")
     end
   end
+
+  WebpackerHelpers.when_webpacker_available do
+    test "it mounts components from the dev server" do
+      WebpackerHelpers.with_dev_server do
+        get :show, id: 1, prerender: true
+        assert_match /Hello<!--.*--> from Webpacker/, response.body
+        get :show, id: 1, prerender: true, greeting: "Howdy"
+        assert_match /Howdy<!--.*--> from Webpacker/, response.body
+      end
+    end
+  end
 end

test/react/rails/webpacker_test.rb

@@ -13,7 +13,7 @@ class ReactRailsWebpackerTest < ActionDispatch::IntegrationTest
       WebpackerHelpers.clear_webpacker_packs
     end
 
-    test 'it mounts pages from the pack' do
+    test 'it mounts components from the pack' do
       visit '/pack_component'
       assert page.has_content?('Export Default')
       assert page.has_content?('Named Export')

test/react/server_rendering/webpacker_manifest_container_test.rb

@@ -18,55 +18,14 @@ class WebpackerManifestContainerTest < ActiveSupport::TestCase
     end
 
     def test_it_loads_from_webpack_dev_server
-      webpack_dev_server = fork do
-        Dir.chdir("test/dummy") do
-          exec "RAILS_ENV=development ./bin/webpack-dev-server "
-        end
+      WebpackerHelpers.with_dev_server do
+        container = React::ServerRendering::WebpackerManifestContainer.new
+        js_file = container.find_asset("application.js")
+        # Main file:
+        assert_includes js_file, "ReactRailsUJS.loadContext(ctx)"
+        # Bundled dependencies:
+        assert_includes js_file, "ExportDefaultComponent"
       end
-
-      detected_dev_server = false
-      60.times do |i|
-        begin
-          # Make sure that the manifest has been updated:
-          Webpacker::Manifest.load("./test/dummy/public/packs/manifest.json")
-          webpack_manifest = Webpacker::Manifest.instance.data
-          example_asset_path = webpack_manifest.values.first
-          if example_asset_path.nil?
-            puts "Manifest is blank, all manifests:"
-            Dir.glob("./test/dummy/public/packs/*.json").each do |f|
-              puts f
-              puts File.read(f)
-            end
-            next
-          end
-          assert_includes example_asset_path, "http://localhost:8080"
-          # Make sure the dev server is up:
-          open("http://localhost:8080/application.js")
-          detected_dev_server = true
-          break
-        rescue StandardError => err
-          puts err.message
-        ensure
-          sleep 0.5
-          puts i
-        end
-      end
-
-      # If we didn't hook up with a dev server after 10s,
-      # fail loudly.
-      assert detected_dev_server
-
-      container = React::ServerRendering::WebpackerManifestContainer.new
-      js_file = container.find_asset("application.js")
-      # Main file:
-      assert_includes js_file, "ReactRailsUJS.loadContext(ctx)"
-      # Bundled dependencies:
-      assert_includes js_file, "ExportDefaultComponent"
-    ensure
-      Process.kill(9, webpack_dev_server)
-      Process.wait
-      # Remove the dev-server packs:
-      WebpackerHelpers.clear_webpacker_packs
     end
   end
 end

test/support/webpacker_helpers.rb

@@ -34,4 +34,81 @@ def compile_if_missing
   def clear_webpacker_packs
     FileUtils.rm_rf(PACKS_DIRECTORY)
   end
+
+  # Start a webpack-dev-server
+  # Call the block
+  # Make sure to clean up the server
+  def with_dev_server
+    # Start the server in a forked process:
+    webpack_dev_server = Dir.chdir("test/dummy") do
+      spawn "RAILS_ENV=development ./bin/webpack-dev-server "
+    end
+
+    detected_dev_server = false
+
+    # Wait for it to start up, make sure it's there by connecting to it:
+    30.times do |i|
+      begin
+        # Make sure that the manifest has been updated:
+        Webpacker::Manifest.load("./test/dummy/public/packs/manifest.json")
+        webpack_manifest = Webpacker::Manifest.instance.data
+        example_asset_path = webpack_manifest.values.first
+        if example_asset_path.nil?
+          # Debug helper
+          # puts "Manifest is blank, all manifests:"
+          # Dir.glob("./test/dummy/public/packs/*.json").each do |f|
+          #   puts f
+          #   puts File.read(f)
+          # end
+          next
+        end
+        # Make sure the dev server is up:
+        open("http://localhost:8080/application.js")
+        if !example_asset_path.start_with?("http://localhost:8080")
+          raise "Manifest doesn't include absolute path to dev server"
+        end
+
+        detected_dev_server = true
+        break
+      rescue StandardError => err
+        puts err.message
+      ensure
+        sleep 0.5
+        # debug counter
+        # puts i
+      end
+    end
+
+    # If we didn't hook up with a dev server after waiting, fail loudly.
+    if !detected_dev_server
+      raise "Failed to start dev server"
+    end
+
+    # Call the test block:
+    yield
+  ensure
+    # Kill the server process
+    # puts "Killing webpack dev server"
+    check_cmd = "lsof -i :8080 -S"
+    10.times do
+      # puts check_cmd
+      status = `#{check_cmd}`
+      # puts status
+      remaining_pid_match = status.match(/\n[a-z]+\s+(\d+)/)
+      if remaining_pid_match
+        remaining_pid = remaining_pid_match[1]
+        # puts "Remaining #{remaining_pid}"
+        kill_cmd = "kill -9 #{remaining_pid}"
+        # puts kill_cmd
+        `#{kill_cmd}`
+        sleep 0.5
+      else
+        break
+      end
+    end
+
+    # Remove the dev-server packs:
+    WebpackerHelpers.clear_webpacker_packs
+    # puts "Killed."
+  end
 end