CodeSampleX

Sample

@jest/environment 30.4.1: JestEnvironment lifecycle and context configuration for @jest/environment 30.4.1

Verified sample for npm @jest/environment 30.4.1: JestEnvironment lifecycle and context configuration for @jest/environment 30.4.1. The contract ran on node…

sha256:a0064c1f4868cb0a05d944022aeac7b796fdeac311c27f247caf64ec9197b648

This network offers one thing: a sample that builds. It ran the sample in a sandbox and kept the signed receipt. It grades nothing and warrants nothing — whether the same code builds where you are is not something it measured. How many distinct signing keys filed a passing contract receipt. One is the author alone; more than one means somebody else built it too. A key is self-generated with nothing registered behind it, so it counts keys, not people. MIT-0

Execution evidence

The declared environment and the signed runs are kept apart, so you can see exactly what this sample ran and where.

Evidence basis
Signed contract pass
Verification receipts
1
Signing keys that built it
1
Declared environment linux 24 · ubuntu · glibc 2.39 x64 npm

Verification-run environments

Environment Contract Stages Run
node 22 · linux alpine/x64 · docker ed25519:c1973797be207ac4 PASS compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS
CONTAINER_RUN · node-typescript@1node:22-alpine@sha256:c610fcdfb1d5…		 2026-08-27

Case

HOW
Goal
JestEnvironment lifecycle and context configuration for @jest/environment 30.4.1
Packages
Symbols
  • JestEnvironment
Created
2026-08-27T22:41:58Z

Contract

  1. @jest/environment package.json declares type definitions entry point ./build/index.d.ts and version 30.4.1
  2. @jest/environment index.d.ts declares JestEnvironment class with constructor, global, fakeTimers, moduleMocker, getVmContext, setup, and teardown methods
  3. @jest/environment index.d.ts declares JestEnvironmentConfig interface containing projectConfig and globalConfig
  4. @jest/environment index.d.ts declares EnvironmentContext type containing console, docblockPragmas, and testPath
  5. @jest/environment index.d.ts declares Jest interface with fake timer controls, module mocking, timer tick mode, and test retries
  6. @jest/environment index.d.ts declares ModuleWrapper and JestImportMeta type definitions
  7. CustomTestEnvironment initializes with JestEnvironmentConfig and EnvironmentContext and exposes global state and lifecycle hooks
  8. CustomTestEnvironment setup and teardown manage environment lifecycle and handleTestEvent processes test runner events

Files

  • PROMPT.md
  • csx.json
  • index.mjs
  • package-lock.json
  • package.json
  • spec.json
  • test/contract.mjs

Download the source artifact (tar.gz)

Source

PROMPT.md
Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: JestEnvironment lifecycle and context configuration for @jest/environment 30.4.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40jest/environment@30.4.1
Demonstrate these symbols/APIs:
  - JestEnvironment

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.
csx.json
{"case":{"caseId":"case:sha256:3a524e14b2adf312e5d2fffd3c81f7772e9d29f69b723e5c834cd680a578273e","contract":["@jest/environment package.json declares type definitions entry point ./build/index.d.ts and version 30.4.1","@jest/environment index.d.ts declares JestEnvironment class with constructor, global, fakeTimers, moduleMocker, getVmContext, setup, and teardown methods","@jest/environment index.d.ts declares JestEnvironmentConfig interface containing projectConfig and globalConfig","@jest/environment index.d.ts declares EnvironmentContext type containing console, docblockPragmas, and testPath","@jest/environment index.d.ts declares Jest interface with fake timer controls, module mocking, timer tick mode, and test retries","@jest/environment index.d.ts declares ModuleWrapper and JestImportMeta type definitions","CustomTestEnvironment initializes with JestEnvironmentConfig and EnvironmentContext and exposes global state and lifecycle hooks","CustomTestEnvironment setup and teardown manage environment lifecycle and handleTestEvent processes test runner events"],"goal":"JestEnvironment lifecycle and context configuration for @jest/environment 30.4.1","kind":"HOW","packages":["pkg:npm/%40jest/environment@30.4.1"],"schemaVersion":1,"symbols":["JestEnvironment"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/%40jest/environment@30.4.1"],"schemaVersion":1,"subject":"pkg:npm/%40jest/environment@30.4.1","symbols":["JestEnvironment"],"verifierAdapter":"node-typescript@1"}
index.mjs
/**
 * Custom Jest Environment conforming to @jest/environment JestEnvironment interface
 */
export class CustomTestEnvironment {
  constructor(config, context) {
    this.config = config;
    this.context = context;
    this.global = {
      ...globalThis,
      testPath: context.testPath,
      customGlobalVar: 'custom_jest_environment_active',
    };
    this.fakeTimers = null;
    this.fakeTimersModern = null;
    this.moduleMocker = null;
    this._isTornDown = false;
  }

  async setup() {
    this.global.__ENVIRONMENT_READY__ = true;
  }

  async teardown() {
    this._isTornDown = true;
    this.global.__ENVIRONMENT_READY__ = false;
  }

  getVmContext() {
    return null;
  }

  handleTestEvent(event, state) {
    if (event.name === 'test_start') {
      this.global.__LAST_TEST_STARTED__ = event.test.name;
    }
  }

  exportConditions() {
    return ['node', 'jest-environment'];
  }
}

export function createEnvironmentContext(testPath, docblockPragmas = {}, customConsole = console) {
  return {
    testPath,
    docblockPragmas,
    console: customConsole,
  };
}

export function createJestEnvironmentConfig(projectConfigOverrides = {}, globalConfigOverrides = {}) {
  return {
    projectConfig: {
      rootDir: '/root',
      testEnvironment: 'node',
      ...projectConfigOverrides,
    },
    globalConfig: {
      rootDir: '/root',
      maxWorkers: 1,
      ...globalConfigOverrides,
    },
  };
}
package-lock.json
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  "name": "sample-jest-environment",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-jest-environment",
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      }
    },
    "node_modules/@babel/code-frame": {
      "version": "7.29.7",
      "resolved": "https://registry.npmjs.org/@babel/code-frame/-/code-frame-7.29.7.tgz",
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      "license": "MIT",
      "dependencies": {
        "@babel/helper-validator-identifier": "^7.29.7",
        "js-tokens": "^4.0.0",
        "picocolors": "^1.1.1"
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    },
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package.json
{
  "name": "sample-jest-environment",
  "version": "1.0.0",
  "type": "module",
  "description": "Clean-room verification sample for @jest/environment",
  "license": "MIT-0",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "@jest/environment": "30.4.1"
  }
}
spec.json
{
  "schemaVersion": 1,
  "goal": "JestEnvironment lifecycle and context configuration for @jest/environment 30.4.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40jest/environment@30.4.1"
  ],
  "symbols": [
    "JestEnvironment"
  ]
}
test/contract.mjs
import assert from 'node:assert/strict';
import fs from 'node:fs';
import path from 'node:path';
import { createRequire } from 'node:module';
import {
  CustomTestEnvironment,
  createEnvironmentContext,
  createJestEnvironmentConfig,
} from '../index.mjs';

const require = createRequire(import.meta.url);

// 1. @jest/environment package.json declares type definitions entry point ./build/index.d.ts and version 30.4.1
const pkgJsonPath = require.resolve('@jest/environment/package.json');
const pkgJson = JSON.parse(fs.readFileSync(pkgJsonPath, 'utf8'));
assert.equal(pkgJson.name, '@jest/environment');
assert.equal(pkgJson.version, '30.4.1');
assert.equal(pkgJson.types, './build/index.d.ts');
assert.equal(pkgJson.exports['.'].types, './build/index.d.ts');

// 2. @jest/environment index.d.ts declares JestEnvironment class with constructor, global, fakeTimers, moduleMocker, getVmContext, setup, and teardown methods
const dtsPath = path.resolve(path.dirname(pkgJsonPath), pkgJson.types);
assert.ok(fs.existsSync(dtsPath));
const dtsContent = fs.readFileSync(dtsPath, 'utf8');

assert.ok(dtsContent.includes('export declare class JestEnvironment<Timer = unknown> {'));
assert.ok(dtsContent.includes('constructor(config: JestEnvironmentConfig, context: EnvironmentContext);'));
assert.ok(dtsContent.includes('global: Global_2.Global;'));
assert.ok(dtsContent.includes('fakeTimers: LegacyFakeTimers<Timer> | null;'));
assert.ok(dtsContent.includes('fakeTimersModern: ModernFakeTimers | null;'));
assert.ok(dtsContent.includes('moduleMocker: ModuleMocker | null;'));
assert.ok(dtsContent.includes('getVmContext(): Context | null;'));
assert.ok(dtsContent.includes('setup(): Promise<void>;'));
assert.ok(dtsContent.includes('teardown(): Promise<void>;'));
assert.ok(dtsContent.includes('handleTestEvent?: Circus.EventHandler;'));

// 3. @jest/environment index.d.ts declares JestEnvironmentConfig interface containing projectConfig and globalConfig
assert.ok(dtsContent.includes('export declare interface JestEnvironmentConfig {'));
assert.ok(dtsContent.includes('projectConfig: Config.ProjectConfig;'));
assert.ok(dtsContent.includes('globalConfig: Config.GlobalConfig;'));

// 4. @jest/environment index.d.ts declares EnvironmentContext type containing console, docblockPragmas, and testPath
assert.ok(dtsContent.includes('export declare type EnvironmentContext = {'));
assert.ok(dtsContent.includes('console: Console;'));
assert.ok(dtsContent.includes('docblockPragmas: Record<string, string | Array<string>>;'));
assert.ok(dtsContent.includes('testPath: string;'));

// 5. @jest/environment index.d.ts declares Jest interface with fake timer controls, module mocking, timer tick mode, and test retries
assert.ok(dtsContent.includes('export declare interface Jest {'));
assert.ok(dtsContent.includes('advanceTimersByTime(msToRun: number | TemporalDurationLike): void;'));
assert.ok(dtsContent.includes('advanceTimersToNextTimer(steps?: number): void;'));
assert.ok(dtsContent.includes('useFakeTimers('));
assert.ok(dtsContent.includes('useRealTimers(): Jest;'));
assert.ok(dtsContent.includes('setTimerTickMode('));
assert.ok(dtsContent.includes('mock<T = unknown>('));
assert.ok(dtsContent.includes("fn: ModuleMocker['fn'];"));
assert.ok(dtsContent.includes("spyOn: ModuleMocker['spyOn'];"));
assert.ok(dtsContent.includes('retryTimes('));

// 6. @jest/environment index.d.ts declares ModuleWrapper and JestImportMeta type definitions
assert.ok(dtsContent.includes('export declare interface JestImportMeta extends ImportMeta {'));
assert.ok(dtsContent.includes('export declare type ModuleWrapper = ('));

// 7. CustomTestEnvironment initializes with JestEnvironmentConfig and EnvironmentContext and exposes global state and lifecycle hooks
const config = createJestEnvironmentConfig({ testEnvironment: 'custom' });
const context = createEnvironmentContext('/project/test/example.test.js', { customPragma: 'true' });
const env = new CustomTestEnvironment(config, context);

assert.equal(env.config.projectConfig.testEnvironment, 'custom');
assert.equal(env.context.testPath, '/project/test/example.test.js');
assert.equal(env.global.testPath, '/project/test/example.test.js');
assert.equal(env.global.customGlobalVar, 'custom_jest_environment_active');
assert.equal(env.getVmContext(), null);
assert.deepEqual(env.exportConditions(), ['node', 'jest-environment']);

// 8. CustomTestEnvironment setup and teardown manage environment lifecycle and handleTestEvent processes test runner events
await env.setup();
assert.equal(env.global.__ENVIRONMENT_READY__, true);

env.handleTestEvent({ name: 'test_start', test: { name: 'sample suite test case' } });
assert.equal(env.global.__LAST_TEST_STARTED__, 'sample suite test case');

await env.teardown();
assert.equal(env.global.__ENVIRONMENT_READY__, false);
assert.equal(env._isTornDown, true);

console.log('All @jest/environment contract assertions passed.');

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