refactor: make a standard API to run tests inside a worker (#4441)

docs/config/index.md

@@ -256,7 +256,7 @@ Should Vitest process assets (.png, .svg, .jpg, etc) files and resolve them like
 This module will have a default export equal to the path to the asset, if no query is specified.
 
 ::: warning
-At the moment, this option only works with [`vmThreads`](#vmthreads) pool.
+At the moment, this option only works with [`vmThreads`](#vmthreads) and [`vmForks`](#vmForks) pools.
 :::
 
 #### deps.web.transformCss
@@ -269,7 +269,7 @@ Should Vitest process CSS (.css, .scss, .sass, etc) files and resolve them like
 If CSS files are disabled with [`css`](#css) options, this option will just silence `ERR_UNKNOWN_FILE_EXTENSION` errors.
 
 ::: warning
-At the moment, this option only works with [`vmThreads`](#vmthreads) pool.
+At the moment, this option only works with [`vmThreads`](#vmthreads) and [`vmForks`](#vmForks) pools.
 :::
 
 #### deps.web.transformGlobPattern
@@ -282,7 +282,7 @@ Regexp pattern to match external files that should be transformed.
 By default, files inside `node_modules` are externalized and not transformed, unless it's CSS or an asset, and corresponding option is not disabled.
 
 ::: warning
-At the moment, this option only works with [`vmThreads`](#vmthreads) pool.
+At the moment, this option only works with [`vmThreads`](#vmthreads) and [`vmForks`](#vmForks) pools.
 :::
 
 #### deps.interopDefault
@@ -545,7 +545,7 @@ export default defineConfig({
 
 ### poolMatchGlobs <Badge type="info">0.29.4+</Badge>
 
-- **Type:** `[string, 'threads' | 'forks' | 'vmThreads' | 'typescript'][]`
+- **Type:** `[string, 'threads' | 'forks' | 'vmThreads' | 'vmForks' | 'typescript'][]`
 - **Default:** `[]`
 
 Automatically assign pool in which tests will run based on globs. The first match will be used.
@@ -610,7 +610,7 @@ By providing an object instead of a string you can define individual outputs whe
 
 ### pool<NonProjectOption /> <Badge type="info">1.0.0+</Badge>
 
-- **Type:** `'threads' | 'forks' | 'vmThreads'`
+- **Type:** `'threads' | 'forks' | 'vmThreads' | 'vmForks'`
 - **Default:** `'threads'`
 - **CLI:** `--pool=threads`
 
@@ -650,9 +650,13 @@ catch (err) {
 Please, be aware of these issues when using this option. Vitest team cannot fix any of the issues on our side.
 :::
 
+#### vmForks<NonProjectOption />
+
+Similar as `vmThreads` pool but uses `child_process` instead of `worker_threads` via [tinypool](https://github.com/tinylibs/tinypool). Communication between tests and main process is not as fast as with `vmThreads` pool. Process related APIs such as `process.chdir()` are available in `vmForks` pool. Please be aware that this pool has the same pitfalls listed in `vmThreads`. 
+
 ### poolOptions<NonProjectOption /> <Badge type="info">1.0.0+</Badge>
 
-- **Type:** `Record<'threads' | 'forks' | 'vmThreads', {}>`
+- **Type:** `Record<'threads' | 'forks' | 'vmThreads' | 'vmForks', {}>`
 - **Default:** `{}`
 
 #### poolOptions.threads
@@ -873,6 +877,57 @@ Pass additional arguments to `node` process in the VM context. See [Command-line
 Be careful when using, it as some options may crash worker, e.g. --prof, --title. See https://github.com/nodejs/node/issues/41103.
 :::
 
+
+#### poolOptions.vmForks<NonProjectOption />
+
+Options for `vmForks` pool.
+
+```ts
+import { defineConfig } from 'vitest/config'
+
+export default defineConfig({
+  test: {
+    poolOptions: {
+      vmForks: {
+        // VM forks related options here
+      }
+    }
+  }
+})
+```
+
+##### poolOptions.vmForks.maxForks<NonProjectOption />
+
+- **Type:** `number`
+- **Default:** _available CPUs_
+
+Maximum number of threads. You can also use `VITEST_MAX_FORKS` environment variable.
+
+##### poolOptions.vmForks.minForks<NonProjectOption />
+
+- **Type:** `number`
+- **Default:** _available CPUs_
+
+Minimum number of threads. You can also use `VITEST_MIN_FORKS` environment variable.
+
+##### poolOptions.vmForks.memoryLimit<NonProjectOption />
+
+- **Type:** `string | number`
+- **Default:** `1 / CPU Cores`
+
+Specifies the memory limit for workers before they are recycled. This value heavily depends on your environment, so it's better to specify it manually instead of relying on the default. How the value is calculated is described in [`poolOptions.vmThreads.memoryLimit`](#pooloptions-vmthreads-memorylimit)
+
+##### poolOptions.vmForks.execArgv<NonProjectOption />
+
+- **Type:** `string[]`
+- **Default:** `[]`
+
+Pass additional arguments to `node` process in the VM context. See [Command-line API | Node.js](https://nodejs.org/docs/latest/api/cli.html) for more information.
+
+:::warning
+Be careful when using, it as some options may crash worker, e.g. --prof, --title. See https://github.com/nodejs/node/issues/41103.
+:::
+
 ### fileParallelism <Badge type="info">1.1.0+</Badge>
 
 - **Type:** `boolean`
@@ -2064,7 +2119,7 @@ Path to a [workspace](/guide/workspace) config file relative to [root](#root).
 - **Default:** `true`
 - **CLI:** `--no-isolate`, `--isolate=false`
 
-Run tests in an isolated environment. This option has no effect on `vmThreads` pool.
+Run tests in an isolated environment. This option has no effect on `vmThreads` and `vmForks` pools.
 
 Disabling this option might [improve performance](/guide/improving-performance) if your code doesn't rely on side effects (which is usually true for projects with `node` environment).
 

packages/vitest/package.json

@@ -52,6 +52,10 @@
       "types": "./dist/execute.d.ts",
       "default": "./dist/execute.js"
     },
+    "./workers": {
+      "types": "./dist/workers.d.ts",
+      "import": "./dist/workers.js"
+    },
     "./browser": {
       "types": "./dist/browser.d.ts",
       "default": "./dist/browser.js"

packages/vitest/rollup.config.js

@@ -15,27 +15,33 @@ import { defineConfig } from 'rollup'
 const require = createRequire(import.meta.url)
 const pkg = require('./package.json')
 
-const entries = [
-  'src/paths.ts',
-  'src/index.ts',
-  'src/node/cli.ts',
-  'src/node/cli-wrapper.ts',
-  'src/node.ts',
-  'src/suite.ts',
-  'src/browser.ts',
-  'src/runners.ts',
-  'src/environments.ts',
-  'src/runtime/worker.ts',
-  'src/runtime/vm.ts',
-  'src/runtime/child.ts',
-  'src/runtime/entry.ts',
-  'src/runtime/entry-vm.ts',
-  'src/integrations/spy.ts',
-  'src/coverage.ts',
-  'src/public/utils.ts',
-  'src/public/execute.ts',
-  'src/public/reporters.ts',
-]
+const entries = {
+  'path': 'src/paths.ts',
+  'index': 'src/index.ts',
+  'cli': 'src/node/cli.ts',
+  'cli-wrapper': 'src/node/cli-wrapper.ts',
+  'node': 'src/node.ts',
+  'suite': 'src/suite.ts',
+  'browser': 'src/browser.ts',
+  'runners': 'src/runners.ts',
+  'environments': 'src/environments.ts',
+  'spy': 'src/integrations/spy.ts',
+  'coverage': 'src/coverage.ts',
+  'utils': 'src/public/utils.ts',
+  'execute': 'src/public/execute.ts',
+  'reporters': 'src/public/reporters.ts',
+  // TODO: advanced docs
+  'workers': 'src/workers.ts',
+
+  // for performance reasons we bundle them separately so we don't import everything at once
+  'worker': 'src/runtime/worker.ts',
+  'workers/forks': 'src/runtime/workers/forks.ts',
+  'workers/threads': 'src/runtime/workers/threads.ts',
+  'workers/vmThreads': 'src/runtime/workers/vmThreads.ts',
+  'workers/vmForks': 'src/runtime/workers/vmForks.ts',
+
+  'workers/runVmTests': 'src/runtime/runVmTests.ts',
+}
 
 const dtsEntries = {
   index: 'src/index.ts',
@@ -49,6 +55,7 @@ const dtsEntries = {
   utils: 'src/public/utils.ts',
   execute: 'src/public/execute.ts',
   reporters: 'src/public/reporters.ts',
+  workers: 'src/workers.ts',
 }
 
 const external = [

packages/vitest/src/integrations/env/happy-dom.ts

@@ -16,7 +16,7 @@ export default <Environment>({
   transformMode: 'web',
   async setupVM({ happyDOM = {} }) {
     const { Window } = await import('happy-dom')
-    const win = new Window({
+    let win = new Window({
       ...happyDOM,
       console: (console && globalThis.console) ? globalThis.console : undefined,
       url: happyDOM.url || 'http://localhost:3000',
@@ -39,6 +39,7 @@ export default <Environment>({
       },
       async teardown() {
         await teardownWindow(win)
+        win = undefined
       },
     }
   },

packages/vitest/src/integrations/env/jsdom.ts

@@ -48,7 +48,7 @@ export default <Environment>({
       cookieJar = false,
       ...restOptions
     } = jsdom as any
-    const dom = new JSDOM(
+    let dom = new JSDOM(
       html,
       {
         pretendToBeVisual,
@@ -97,6 +97,7 @@ export default <Environment>({
       teardown() {
         clearWindowErrors()
         dom.window.close()
+        dom = undefined as any
       },
     }
   },

packages/vitest/src/integrations/env/loader.ts

@@ -2,7 +2,7 @@ import { normalize, resolve } from 'pathe'
 import { ViteNodeRunner } from 'vite-node/client'
 import type { ViteNodeRunnerOptions } from 'vite-node'
 import type { BuiltinEnvironment, VitestEnvironment } from '../../types/config'
-import type { Environment } from '../../types'
+import type { ContextRPC, Environment, WorkerRPC } from '../../types'
 import { environments } from './index'
 
 function isBuiltinEnvironment(env: VitestEnvironment): env is BuiltinEnvironment {
@@ -20,14 +20,19 @@ export async function createEnvironmentLoader(options: ViteNodeRunnerOptions) {
   return _loaders.get(options.root)!
 }
 
-export async function loadEnvironment(name: VitestEnvironment, options: ViteNodeRunnerOptions): Promise<Environment> {
+export async function loadEnvironment(ctx: ContextRPC, rpc: WorkerRPC): Promise<Environment> {
+  const name = ctx.environment.name
   if (isBuiltinEnvironment(name))
     return environments[name]
-  const loader = await createEnvironmentLoader(options)
+  const loader = await createEnvironmentLoader({
+    root: ctx.config.root,
+    fetchModule: id => rpc.fetch(id, 'ssr'),
+    resolveId: (id, importer) => rpc.resolveId(id, importer, 'ssr'),
+  })
   const root = loader.root
   const packageId = name[0] === '.' || name[0] === '/'
     ? resolve(root, name)
-    : (await options.resolveId!(`vitest-environment-${name}`))?.id ?? resolve(root, name)
+    : (await rpc.resolveId(`vitest-environment-${name}`, undefined, 'ssr'))?.id ?? resolve(root, name)
   const pkg = await loader.executeId(normalize(packageId))
   if (!pkg || !pkg.default || typeof pkg.default !== 'object') {
     throw new TypeError(

packages/vitest/src/integrations/env/node.ts

@@ -36,8 +36,8 @@ export default <Environment>({
   // this is largely copied from jest's node environment
   async setupVM() {
     const vm = await import('node:vm')
-    const context = vm.createContext()
-    const global = vm.runInContext(
+    let context = vm.createContext()
+    let global = vm.runInContext(
       'this',
       context,
     )
@@ -108,7 +108,8 @@ export default <Environment>({
         return context
       },
       teardown() {
-        //
+        context = undefined as any
+        global = undefined
       },
     }
   },

packages/vitest/src/integrations/mock/timers.ts

@@ -13,6 +13,7 @@ import type {
 import {
   withGlobal,
 } from '@sinonjs/fake-timers'
+import { isChildProcess } from '../../utils/base'
 import { RealDate, mockDate, resetDate } from './date'
 
 export class FakeTimers {
@@ -134,8 +135,7 @@ export class FakeTimers {
         // Do not mock nextTick by default. It can still be mocked through userConfig.
         .filter(timer => timer !== 'nextTick') as (keyof FakeTimerWithContext['timers'])[]
 
-      // @ts-expect-error -- untyped internal
-      if (this._userConfig?.toFake?.includes('nextTick') && globalThis.__vitest_worker__.isChildProcess)
+      if (this._userConfig?.toFake?.includes('nextTick') && isChildProcess())
         throw new Error('process.nextTick cannot be mocked inside child_process')
 
       this._clock = this._fakeTimers.install({

packages/vitest/src/integrations/vi.ts

@@ -6,6 +6,7 @@ import type { ResolvedConfig, RuntimeConfig } from '../types'
 import type { MockFactoryWithHelper } from '../types/mocker'
 import { getWorkerState } from '../utils/global'
 import { resetModules, waitForImportsToResolve } from '../utils/modules'
+import { isChildProcess } from '../utils/base'
 import { FakeTimers } from './mock/timers'
 import type { MaybeMocked, MaybeMockedDeep, MaybePartiallyMocked, MaybePartiallyMockedDeep, MockInstance } from './spy'
 import { fn, isMockFunction, mocks, spyOn } from './spy'
@@ -370,7 +371,7 @@ function createVitest(): VitestUtils {
 
   const utils: VitestUtils = {
     useFakeTimers(config?: FakeTimerInstallOpts) {
-      if (workerState.isChildProcess) {
+      if (isChildProcess()) {
         if (config?.toFake?.includes('nextTick') || workerState.config?.fakeTimers?.toFake?.includes('nextTick')) {
           throw new Error(
             'vi.useFakeTimers({ toFake: ["nextTick"] }) is not supported in node:child_process. Use --pool=threads if mocking nextTick is required.',

packages/vitest/src/node/config.ts

@@ -274,6 +274,10 @@ export function resolveConfig(
         ...resolved.poolOptions?.forks,
         maxForks: Number.parseInt(process.env.VITEST_MAX_FORKS),
       },
+      vmForks: {
+        ...resolved.poolOptions?.vmForks,
+        maxForks: Number.parseInt(process.env.VITEST_MAX_FORKS),
+      },
     }
   }
 
@@ -284,6 +288,10 @@ export function resolveConfig(
         ...resolved.poolOptions?.forks,
         minForks: Number.parseInt(process.env.VITEST_MIN_FORKS),
       },
+      vmForks: {
+        ...resolved.poolOptions?.vmForks,
+        minForks: Number.parseInt(process.env.VITEST_MIN_FORKS),
+      },
     }
   }
 

packages/vitest/src/node/core.ts

@@ -59,11 +59,7 @@ export class Vitest {
   public projects: WorkspaceProject[] = []
   private projectsTestFiles = new Map<string, Set<WorkspaceProject>>()
 
-  projectFiles!: {
-    workerPath: string
-    forksPath: string
-    vmPath: string
-  }
+  public distPath!: string
 
   constructor(
     public readonly mode: VitestRunMode,
@@ -102,11 +98,7 @@ export class Vitest {
     // if Vitest is running globally, then we should still import local vitest if possible
     const projectVitestPath = await this.vitenode.resolveId('vitest')
     const vitestDir = projectVitestPath ? resolve(projectVitestPath.id, '../..') : rootDir
-    this.projectFiles = {
-      workerPath: join(vitestDir, 'dist/worker.js'),
-      forksPath: join(vitestDir, 'dist/child.js'),
-      vmPath: join(vitestDir, 'dist/vm.js'),
-    }
+    this.distPath = join(vitestDir, 'dist')
 
     const node = this.vitenode
     this.runner = new ViteNodeRunner({

packages/vitest/src/node/error.ts

@@ -58,8 +58,14 @@ export async function printError(error: unknown, project: WorkspaceProject | und
 
   const nearest = error instanceof TypeCheckError
     ? error.stacks[0]
-    : stacks.find(stack =>
-      project.server && project.getModuleById(stack.file) && existsSync(stack.file),
+    : stacks.find((stack) => {
+      try {
+        return project.server && project.getModuleById(stack.file) && existsSync(stack.file)
+      }
+      catch {
+        return false
+      }
+    },
     )
 
   const errorProperties = getErrorProperties(e)