fix(browser): correctly mock optimized cjs dependencies (#6035)

packages/browser/src/client/tester/mocker.ts

@@ -138,16 +138,24 @@ export class VitestBrowserClientMocker {
   public queueMock(id: string, importer: string, factory?: () => any) {
     const promise = rpc()
       .resolveMock(id, importer, !!factory)
-      .then(async ({ mockPath, resolvedId }) => {
+      .then(async ({ mockPath, resolvedId, needsInterop }) => {
         this.ids.add(resolvedId)
-        const urlPaths = resolveMockPaths(resolvedId)
+        const urlPaths = resolveMockPaths(cleanVersion(resolvedId))
         const resolvedMock
           = typeof mockPath === 'string'
-            ? new URL(resolvedMockedPath(mockPath), location.href).toString()
+            ? new URL(resolvedMockedPath(cleanVersion(mockPath)), location.href).toString()
             : mockPath
+        const _factory = factory && needsInterop
+          ? async () => {
+            const data = await factory()
+            return { default: data }
+          }
+          : factory
         urlPaths.forEach((url) => {
           this.mocks[url] = resolvedMock
-          this.factories[url] = factory!
+          if (_factory) {
+            this.factories[url] = _factory
+          }
         })
         channel.postMessage({
           type: 'mock',
@@ -170,7 +178,7 @@ export class VitestBrowserClientMocker {
           return
         }
         this.ids.delete(resolved.id)
-        const urlPaths = resolveMockPaths(resolved.id)
+        const urlPaths = resolveMockPaths(cleanVersion(resolved.id))
         urlPaths.forEach((url) => {
           delete this.mocks[url]
           delete this.factories[url]
@@ -445,3 +453,8 @@ function resolveMockPaths(path: string) {
 
   return paths
 }
+
+const versionRegexp = /(\?|&)v=\w{8}/
+function cleanVersion(url: string) {
+  return url.replace(versionRegexp, '')
+}

packages/browser/src/client/tester/msw.ts

@@ -13,7 +13,7 @@ export function createModuleMocker() {
 
   const worker = setupWorker(
     http.get(/.+/, async ({ request }) => {
-      const path = removeTimestamp(request.url.slice(location.origin.length))
+      const path = cleanQuery(request.url.slice(location.origin.length))
       if (!mocks.has(path)) {
         return passthrough()
       }
@@ -112,9 +112,9 @@ function getFactoryExports(id: string) {
 }
 
 const timestampRegexp = /(\?|&)t=\d{13}/
-
-function removeTimestamp(url: string) {
-  return url.replace(timestampRegexp, '')
+const versionRegexp = /(\?|&)v=\w{8}/
+function cleanQuery(url: string) {
+  return url.replace(timestampRegexp, '').replace(versionRegexp, '')
 }
 
 function passthrough() {

packages/browser/src/node/resolveMock.ts

@@ -1,8 +1,9 @@
-import { existsSync, readdirSync } from 'node:fs'
+import { existsSync, readFileSync, readdirSync } from 'node:fs'
 import { builtinModules } from 'node:module'
 import { basename, dirname, extname, isAbsolute, join, resolve } from 'pathe'
 import type { PartialResolvedId } from 'rollup'
 import type { ResolvedConfig } from 'vitest'
+import type { ResolvedConfig as ViteConfig } from 'vite'
 import type { WorkspaceProject } from 'vitest/node'
 
 export async function resolveMock(
@@ -14,7 +15,9 @@ export async function resolveMock(
   const { id, fsPath, external } = await resolveId(project, rawId, importer)
 
   if (hasFactory) {
-    return { type: 'factory' as const, resolvedId: id }
+    const needsInteropMap = viteDepsInteropMap(project.browser!.vite.config)
+    const needsInterop = needsInteropMap?.get(fsPath) ?? false
+    return { type: 'factory' as const, resolvedId: id, needsInterop }
   }
 
   const mockPath = resolveMockPath(project.config.root, fsPath, external)
@@ -126,3 +129,29 @@ const postfixRE = /[?#].*$/
 export function cleanUrl(url: string): string {
   return url.replace(postfixRE, '')
 }
+
+const metadata = new WeakMap<ViteConfig, Map<string, boolean>>()
+
+function viteDepsInteropMap(config: ViteConfig) {
+  if (metadata.has(config)) {
+    return metadata.get(config)!
+  }
+  const cacheDirPath = getDepsCacheDir(config)
+  const metadataPath = resolve(cacheDirPath, '_metadata.json')
+  if (!existsSync(metadataPath)) {
+    return null
+  }
+  const { optimized } = JSON.parse(readFileSync(metadataPath, 'utf-8'))
+  const needsInteropMap = new Map()
+  for (const name in optimized) {
+    const dep = optimized[name]
+    const file = resolve(cacheDirPath, dep.file)
+    needsInteropMap.set(file, dep.needsInterop)
+  }
+  metadata.set(config, needsInteropMap)
+  return needsInteropMap
+}
+
+function getDepsCacheDir(config: ViteConfig): string {
+  return resolve(config.cacheDir, 'deps')
+}

packages/browser/src/node/types.ts

@@ -35,6 +35,7 @@ export interface WebSocketBrowserHandlers {
     type: 'factory' | 'redirect' | 'automock'
     mockPath?: string | null
     resolvedId: string
+    needsInterop?: boolean
   }>
   invalidate: (ids: string[]) => void
   getBrowserFileSourceMap: (

test/browser/fixtures/mocking/mocking-dep.test.ts

@@ -0,0 +1,12 @@
+import { a } from '@vitest/cjs-lib'
+import { expect, test, vi } from 'vitest'
+
+vi.mock(import('@vitest/cjs-lib'), () => {
+  return {
+    a: 'mocked',
+  }
+})
+
+test('mocking works correctly', () => {
+  expect(a).toBe('mocked')
+})

test/browser/fixtures/mocking/vitest.config.ts

@@ -5,6 +5,10 @@ const name =
   process.env.BROWSER || (provider === 'playwright' ? 'chromium' : 'chrome')
 
 export default defineConfig({
+  optimizeDeps: {
+    include: ['@vitest/cjs-lib'],
+    needsInterop: ['@vitest/cjs-lib'],
+  },
   test: {
     browser: {
       enabled: true,