Experimental feature changes

packages/next/build/webpack-config.ts

@@ -1013,7 +1013,7 @@ export default async function getBaseWebpackConfig(
           config.experimental.optimizeImages
         ),
         'process.env.__NEXT_OPTIMIZE_CSS': JSON.stringify(
-          !!config.experimental.optimizeCss && !dev
+          config.experimental.optimizeCss && !dev
         ),
         'process.env.__NEXT_SCROLL_RESTORATION': JSON.stringify(
           config.experimental.scrollRestoration
@@ -1202,6 +1202,7 @@ export default async function getBaseWebpackConfig(
       reactMode: config.experimental.reactMode,
       optimizeFonts: config.experimental.optimizeFonts,
       optimizeImages: config.experimental.optimizeImages,
+      optimizeCss: config.experimental.optimizeCss,
       scrollRestoration: config.experimental.scrollRestoration,
       basePath: config.basePath,
       pageEnv: config.experimental.pageEnv,

packages/next/next-server/server/next-server.ts

@@ -1575,6 +1575,8 @@ export default class Server {
               locale,
               locales,
               defaultLocale,
+              optimizeCss: this.renderOpts.optimizeCss,
+              distDir: this.distDir,
               fontManifest: this.renderOpts.fontManifest,
               domainLocales: this.renderOpts.domainLocales,
             }

test/integration/critical-css/pages/index.js

@@ -7,3 +7,5 @@ export default function Home() {
     </div>
   )
 }
+
+Home.getInitialProps = () => ({})

test/integration/critical-css/test/index.test.js

@@ -65,3 +65,21 @@ describe('CSS optimization for serverless apps', () => {
   afterAll(() => killApp(app))
   runTests()
 })
+
+describe('Font optimization for emulated serverless apps', () => {
+  beforeAll(async () => {
+    await fs.writeFile(
+      nextConfig,
+      `module.exports = { target: 'experimental-serverless-trace', experimental: {optimizeCss: true} }`,
+      'utf8'
+    )
+    await nextBuild(appDir)
+    appPort = await findPort()
+    app = await nextStart(appDir, appPort)
+  })
+  afterAll(async () => {
+    await killApp(app)
+    await fs.remove(nextConfig)
+  })
+  runTests()
+})