Fix Pro RSC Rspack runtime readiness

Author: justin808

.github/workflows/pro-integration-tests.yml

@@ -687,8 +687,56 @@ jobs:
             done
           }
 
-          wait_for_service "Rails server" false "http://localhost:3000"
-          wait_for_service "Node renderer" true "http://[::1]:3800/info" "http://127.0.0.1:3800/info"
+          wait_for_h2c_service() {
+            name="$1"
+            authority="$2"
+            path="$3"
+            timeout=300
+            elapsed=0
+
+            while true; do
+              if node - "$authority" "$path" <<'NODE'
+          const http2 = require('node:http2');
+
+          const [authority, path] = process.argv.slice(2);
+          const client = http2.connect(authority);
+          const request = client.request({ ':method': 'GET', ':path': path });
+          let status;
+
+          const fail = () => {
+            client.destroy();
+            process.exit(1);
+          };
+
+          client.on('error', fail);
+          request.on('error', fail);
+          request.on('response', (headers) => {
+            status = headers[':status'];
+          });
+          request.on('data', () => {});
+          request.on('end', () => {
+            client.close();
+            process.exit(status >= 200 && status < 300 ? 0 : 1);
+          });
+          request.end();
+          setTimeout(fail, 2000);
+          NODE
+              then
+                echo "${name} started at ${authority}${path} after ${elapsed}s"
+                return 0
+              fi
+
+              sleep 1
+              elapsed=$((elapsed + 1))
+              if [ $elapsed -ge $timeout ]; then
+                echo "Timeout waiting for ${name} to start after ${timeout}s"
+                exit 1
+              fi
+            done
+          }
+
+          wait_for_service "Rails server" true "http://localhost:3000/empty"
+          wait_for_h2c_service "Node renderer" "http://[::1]:3800" "/info"
 
       - name: Install Playwright dependencies
         run: cd spec/dummy && npx playwright install --with-deps

react_on_rails_pro/spec/dummy/bin/shakapacker

@@ -4,7 +4,7 @@
 require "pathname"
 
 ENV["RAILS_ENV"] ||= "development"
-ENV["NODE_ENV"] ||= ENV.fetch("RAILS_ENV")
+ENV["NODE_ENV"] ||= ENV.fetch("RAILS_ENV", "development")
 ENV["BUNDLE_GEMFILE"] ||= File.expand_path("../../Gemfile", Pathname.new(__FILE__).realpath)
 
 require "bundler/setup"

react_on_rails_pro/spec/dummy/config/rspack/rspack.config.js

@@ -1,5 +1,15 @@
 // Set this before loading the shared webpack config because Shakapacker reads
 // the assets_bundler setting while its config module is required.
+const previousAssetsBundler = process.env.SHAKAPACKER_ASSETS_BUNDLER;
 process.env.SHAKAPACKER_ASSETS_BUNDLER = 'rspack';
 
-module.exports = require('../webpack/webpack.config');
+try {
+  // eslint-disable-next-line global-require
+  module.exports = require('../webpack/webpack.config');
+} finally {
+  if (previousAssetsBundler === undefined) {
+    delete process.env.SHAKAPACKER_ASSETS_BUNDLER;
+  } else {
+    process.env.SHAKAPACKER_ASSETS_BUNDLER = previousAssetsBundler;
+  }
+}

react_on_rails_pro/spec/dummy/tests/rsc-rspack-config.test.js

@@ -5,6 +5,12 @@ const rspackConfigPath = path.resolve(__dirname, '../config/rspack/rspack.config
 const shakapackerBinPath = path.resolve(__dirname, '../bin/shakapacker');
 const clientConfigPath = path.resolve(__dirname, '../config/webpack/clientWebpackConfig.js');
 const serverConfigPath = path.resolve(__dirname, '../config/webpack/serverWebpackConfig.js');
+const rscConfigPath = path.resolve(__dirname, '../config/webpack/rscWebpackConfig.js');
+
+afterEach(() => {
+  jest.resetModules();
+  jest.clearAllMocks();
+});
 
 describe('Pro dummy RSC rspack config', () => {
   it('provides a rspack entrypoint that delegates to the shared build config', () => {
@@ -46,4 +52,51 @@ describe('Pro dummy RSC rspack config', () => {
     expect(clientSource).toContain('path: false');
     expect(clientSource).toContain('stream: false');
   });
+
+  it('wraps function-shaped JavaScript loader rules once for the RSC loader', () => {
+    jest.doMock('shakapacker', () => ({
+      config: {
+        source_entry_path: 'packs',
+        source_path: 'client/app',
+      },
+    }));
+
+    const functionRule = {
+      use() {
+        return [{ loader: 'babel-loader', options: { caller: { ssr: true } } }];
+      },
+    };
+    const serverConfig = {
+      entry: { 'server-bundle': './server-bundle.js' },
+      module: { rules: [functionRule] },
+      output: {},
+      plugins: [],
+      resolve: { alias: {} },
+    };
+    const configureServer = jest.fn(() => serverConfig);
+    const extractLoader = (rule, loaderName) =>
+      Array.isArray(rule.use) ? rule.use.find((item) => item?.loader?.includes(loaderName)) : null;
+
+    jest.doMock(serverConfigPath, () => ({
+      default: configureServer,
+      extractLoader,
+    }));
+
+    // eslint-disable-next-line global-require, import/no-dynamic-require
+    const configureRsc = require(rscConfigPath);
+    const firstConfig = configureRsc();
+    const wrappedUse = firstConfig.module.rules[0].use;
+    const firstUseResult = wrappedUse({});
+
+    configureRsc();
+    const secondUseResult = firstConfig.module.rules[0].use({});
+
+    expect(configureServer).toHaveBeenCalledWith(true);
+    expect(wrappedUse.name).toBe('rscLoaderWrapper');
+    expect(firstUseResult).toEqual([
+      { loader: 'babel-loader', options: { caller: { ssr: true } } },
+      { loader: 'react-on-rails-rsc/WebpackLoader' },
+    ]);
+    expect(secondUseResult).toEqual(firstUseResult);
+  });
 });