test(test-utils): utility for --turbo testing

packages/next/build/swc/index.js

@@ -410,6 +410,9 @@ function loadNative(isCustomTurbopack = false) {
                   ...process.env,
                 },
               })
+              child.on('message', (message) => {
+                console.log(message)
+              })
               child.on('close', (code) => {
                 if (code !== 0) {
                   reject({

test/lib/e2e-utils.ts

@@ -4,6 +4,7 @@ import { NextInstance, NextInstanceOpts } from './next-modes/base'
 import { NextDevInstance } from './next-modes/next-dev'
 import { NextStartInstance } from './next-modes/next-start'
 import { NextDeployInstance } from './next-modes/next-deploy'
+import { shouldRunTurboDevTest } from './next-test-utils'
 
 // increase timeout to account for yarn install time
 jest.setTimeout(240 * 1000)
@@ -117,6 +118,10 @@ export async function createNext(
       throw new Error(`createNext called without destroying previous instance`)
     }
 
+    if (!opts['turbo']) {
+      opts.turbo = shouldRunTurboDevTest()
+    }
+
     if (testMode === 'dev') {
       // next dev
       nextInstance = new NextDevInstance(opts)

test/lib/next-test-utils.js

@@ -345,8 +345,16 @@ export function runNextCommandDev(argv, stdOut, opts = {}) {
 
 // Launch the app in dev mode.
 export function launchApp(dir, port, opts) {
-  const { turbo, ...options } = opts ?? {}
-  const useTurbo = !process.env.TEST_WASM && turbo
+  const options = opts ?? {}
+  let useTurbo = false
+
+  if (!process.env.TEST_WASM) {
+    if (options['turbo']) {
+      useTurbo = options.turbo
+    } else {
+      useTurbo = shouldRunTurboDevTest()
+    }
+  }
 
   return runNextCommandDev(
     [useTurbo ? '--turbo' : undefined, dir, '-p', port].filter(Boolean),
@@ -867,3 +875,47 @@ export function findAllTelemetryEvents(output, eventName) {
   )
   return events.filter((e) => e.eventName === eventName).map((e) => e.payload)
 }
+
+/**
+ * Utility function to determine if a given test case needs to run with --turbo.
+ *
+ * This is primarily for the gradual test enablement with latest turbopack upstream changes.
+ *
+ * Note: it could be possible to dynamically create test cases itself (createDevTest(): it.each([...])), but
+ * it makes hard to conform with existing lint rules. Instead, starting off from manual fixture setup and
+ * update test cases accordingly as turbopack changes enable more test cases.
+ */
+export function shouldRunTurboDevTest() {
+  const shouldRunTurboDev = !!process.env.__INTERNAL_NEXT_DEV_TEST_TURBO_DEV
+  // short-circuit to run all the test with --turbo enabled skips glob matching costs
+  if (shouldRunTurboDev) {
+    console.log(
+      `Running tests with --turbo via custom environment variable __INTERNAL_NEXT_DEV_TEST_TURBO_DEV`
+    )
+    return true
+  }
+
+  const shouldRunTurboDevWithMatches =
+    !!process.env.__INTERNAL_NEXT_DEV_TEST_TURBO_GLOB_MATCH
+
+  // By default, we do not run any tests with `--turbo` flag.
+  if (!shouldRunTurboDevWithMatches) {
+    return false
+  }
+
+  const glob = require('glob')
+  const matches = glob.sync(
+    process.env.__INTERNAL_NEXT_DEV_TEST_TURBO_GLOB_MATCH
+  )
+  const testPath = expect.getState().testPath
+  const isMatch = matches.some((match) => testPath.includes(match))
+
+  if (isMatch) {
+    console.log(
+      `Running tests with --turbo via custom environment variable __INTERNAL_NEXT_DEV_TEST_TURBO_GLOB_MATCH`
+    )
+  }
+
+  // If the test path matches the glob pattern, add additional case to run the test with `--turbo` flag.
+  return isMatch
+}