@vitest/expect 3.2.7

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: verify pkg:npm/%40vitest/expect@3.2.7
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40vitest/expect@3.2.7
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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.

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{
  "name": "sample-vitest-expect",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
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      "license": "MIT"
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      "funding": {
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}

{
  "name": "sample-vitest-expect",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "description": "Clean-room verification for @vitest/expect",
  "main": "src/index.mjs",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "@vitest/expect": "3.2.7"
  },
  "license": "MIT-0"
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/%40vitest/expect@3.2.7",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40vitest/expect@3.2.7"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

import * as chai from 'chai';
import {
  JestChaiExpect,
  JestAsymmetricMatchers,
  JestExtend,
  equals,
  subsetEquality,
  iterableEquality,
  StringContaining,
  ArrayContaining,
  ObjectContaining,
  Any,
  Anything,
  StringMatching,
  getState,
  setState,
  customMatchers
} from '@vitest/expect';

// Initialize Chai with @vitest/expect plugins
chai.use(JestChaiExpect);
chai.use(JestAsymmetricMatchers);
chai.use(JestExtend);

const { expect } = chai;

/**
 * Validates value equality using equals utility.
 * @param {unknown} actual
 * @param {unknown} expected
 * @returns {boolean}
 */
export function checkEquality(actual, expected) {
  return equals(actual, expected);
}

/**
 * Validates subset relationship using subsetEquality utility.
 * @param {unknown} object
 * @param {unknown} subset
 * @returns {boolean}
 */
export function checkSubset(object, subset) {
  return Boolean(subsetEquality(object, subset));
}

/**
 * Validates iterable equality using iterableEquality utility.
 * @param {unknown} a
 * @param {unknown} b
 * @returns {boolean}
 */
export function checkIterableEquality(a, b) {
  return Boolean(iterableEquality(a, b));
}

/**
 * Creates an Any asymmetric matcher instance.
 * @param {unknown} sampleType
 * @returns {Any}
 */
export function createAnyMatcher(sampleType) {
  return new Any(sampleType);
}

/**
 * Creates a StringContaining asymmetric matcher instance.
 * @param {string} substring
 * @returns {StringContaining}
 */
export function createStringContainingMatcher(substring) {
  return new StringContaining(substring);
}

/**
 * Registers custom matcher using expect.extend.
 * @param {Record<string, Function>} matchers
 */
export function registerCustomMatchers(matchers) {
  expect.extend(expect, matchers);
}

export {
  expect,
  JestChaiExpect,
  JestAsymmetricMatchers,
  JestExtend,
  equals,
  subsetEquality,
  iterableEquality,
  StringContaining,
  ArrayContaining,
  ObjectContaining,
  Any,
  Anything,
  StringMatching,
  getState,
  setState,
  customMatchers
};

import assert from 'node:assert';
import {
  expect,
  checkEquality,
  checkSubset,
  checkIterableEquality,
  createAnyMatcher,
  createStringContainingMatcher,
  registerCustomMatchers,
  getState,
  setState,
  StringContaining,
  ArrayContaining,
  ObjectContaining,
  Any,
  Anything,
  StringMatching
} from '../src/index.mjs';

// 1. JestChaiExpect plugin integrates Jest-compatible expect matchers into Chai
expect(42).toBe(42);
expect(42).not.toBe(100);
expect({ key: 'val', list: [1, 2] }).toEqual({ key: 'val', list: [1, 2] });
expect({ a: 1, b: 2, c: 3 }).toMatchObject({ a: 1, b: 2 });
expect([10, 20, 30]).toContain(20);
expect('clean-room testing').toContain('clean-room');
expect('pattern-123').toMatch(/^[a-z]+-\d+$/);
expect(true).toBeTruthy();
expect(false).toBeFalsy();
expect(null).toBeNull();
expect(undefined).toBeUndefined();
expect(NaN).toBeNaN();
expect(() => {
  throw new Error('expected failure message');
}).toThrow('expected failure message');

// 2. JestAsymmetricMatchers provides asymmetric matchers like any, stringContaining, arrayContaining, objectContaining, and anything
const payload = {
  id: 101,
  title: 'sample contract test',
  items: ['alpha', 'beta', 'gamma'],
  metadata: { active: true, priority: 1 },
  arbitrary: 'present'
};

expect(payload).toEqual({
  id: expect.any(Number),
  title: expect.stringContaining('contract'),
  items: expect.arrayContaining(['beta']),
  metadata: expect.objectContaining({ active: true }),
  arbitrary: expect.anything()
});

// 3. Asymmetric matcher classes evaluate matching correctly
const stringMatcher = createStringContainingMatcher('contract');
assert.strictEqual(stringMatcher.asymmetricMatch('sample contract test'), true, 'StringContaining should match substring');
assert.strictEqual(stringMatcher.asymmetricMatch('other test'), false, 'StringContaining should not match non-substring');

const numberMatcher = createAnyMatcher(Number);
assert.strictEqual(numberMatcher.asymmetricMatch(12345), true, 'Any(Number) should match numbers');
assert.strictEqual(numberMatcher.asymmetricMatch('12345'), false, 'Any(Number) should not match strings');

const anythingMatcher = new Anything();
assert.strictEqual(anythingMatcher.asymmetricMatch('hello'), true, 'Anything should match strings');
assert.strictEqual(anythingMatcher.asymmetricMatch(0), true, 'Anything should match zero');
assert.strictEqual(anythingMatcher.asymmetricMatch(null), false, 'Anything should reject null');
assert.strictEqual(anythingMatcher.asymmetricMatch(undefined), false, 'Anything should reject undefined');

const arrayMatcher = new ArrayContaining(['alpha', 'gamma']);
assert.strictEqual(arrayMatcher.asymmetricMatch(['alpha', 'beta', 'gamma']), true, 'ArrayContaining should match subset array');
assert.strictEqual(arrayMatcher.asymmetricMatch(['beta', 'delta']), false, 'ArrayContaining should reject missing elements');

const objMatcher = new ObjectContaining({ active: true });
assert.strictEqual(objMatcher.asymmetricMatch({ active: true, priority: 1 }), true, 'ObjectContaining should match object subset');
assert.strictEqual(objMatcher.asymmetricMatch({ active: false, priority: 1 }), false, 'ObjectContaining should reject mismatched property');

const regexMatcher = new StringMatching(/^sample/);
assert.strictEqual(regexMatcher.asymmetricMatch('sample test'), true, 'StringMatching should match regexp');
assert.strictEqual(regexMatcher.asymmetricMatch('other test'), false, 'StringMatching should reject non-matching string');

// 4. Standalone utility functions (equals, subsetEquality, iterableEquality) verify structural and subset equality
assert.strictEqual(checkEquality({ a: 1, b: [2] }, { a: 1, b: [2] }), true, 'equals should return true for equal objects');
assert.strictEqual(checkEquality({ a: 1 }, { a: 2 }), false, 'equals should return false for unequal objects');

assert.strictEqual(checkSubset({ x: 10, y: 20, z: 30 }, { x: 10, z: 30 }), true, 'subsetEquality should return true for valid subset');
assert.strictEqual(checkSubset({ x: 10 }, { x: 99 }), false, 'subsetEquality should return false for differing values');

assert.strictEqual(checkIterableEquality(new Set([1, 2, 3]), new Set([3, 2, 1])), true, 'iterableEquality should match unordered sets');

// 5. getState and setState inspect and update matcher state
setState({ testRunId: 'sample-run-1' }, expect);
const state = getState(expect);
assert.strictEqual(state.testRunId, 'sample-run-1', 'getState should retrieve updated matcher state');

// 6. expect.extend registers custom matchers
registerCustomMatchers({
  toBePositiveEven(received) {
    const pass = typeof received === 'number' && received > 0 && received % 2 === 0;
    return {
      pass,
      message: () => pass
        ? `expected ${received} not to be a positive even number`
        : `expected ${received} to be a positive even number`
    };
  }
});

expect(8).toBePositiveEven();
expect(-4).not.toBePositiveEven();
expect(7).not.toBePositiveEven();

console.log('Contract tests passed successfully.');