@vitest/expect 2.1.9

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@2.1.9
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40vitest/expect@2.1.9
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.

{"case":{"caseId":"case:sha256:08b007b06b5c54ddf5c834e4b5ea36f69c53f0cd36830c5464621d1787642874","constraints":{"executionContext":"node"},"contract":["createExpect configures Chai with JestChaiExpect, JestAsymmetricMatchers, and JestExtend","toBe and toEqual perform primitive value and deep equality assertions","toMatchObject and toHaveProperty verify subset structures and nested object properties","toContain and toContainEqual assert element presence in arrays and strings","toBeGreaterThan, toBeLessThan, and toBeCloseTo validate numeric relationships and floating point values","toBeTypeOf and toSatisfy evaluate type classifications and custom predicate functions","toThrow verifies exception throwing and error type matching","Asymmetric matchers StringContaining, StringMatching, ObjectContaining, and ArrayContaining match partial values","expect.extend registers custom matchers with custom pass and failure message logic","getState and setState inspect and update matcher execution context"],"goal":"verify pkg:npm/%40vitest/expect@2.1.9","kind":"HOW","packages":["pkg:npm/%40vitest/expect@2.1.9"],"schemaVersion":1},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/%40vitest/expect@2.1.9"],"schemaVersion":1,"subject":"pkg:npm/%40vitest/expect@2.1.9","verifierAdapter":"node-typescript@1"}

import * as chai from 'chai';
import {
  JestChaiExpect,
  JestAsymmetricMatchers,
  JestExtend,
  getState,
  setState,
  equals,
  isA,
  isAsymmetric,
  hasAsymmetric,
  StringContaining,
  StringMatching,
  ObjectContaining,
  ArrayContaining,
  Any,
  Anything,
  addCustomEqualityTesters,
  getObjectSubset
} from '@vitest/expect';

export function createExpect() {
  chai.use(JestChaiExpect);
  chai.use(JestAsymmetricMatchers);
  chai.use(JestExtend);
  return chai.expect;
}

export const expect = createExpect();

export function extendExpect(expectInstance, customMatchers) {
  expectInstance.extend(expectInstance, customMatchers);
}

export {
  JestChaiExpect,
  JestAsymmetricMatchers,
  JestExtend,
  getState,
  setState,
  equals,
  isA,
  isAsymmetric,
  hasAsymmetric,
  StringContaining,
  StringMatching,
  ObjectContaining,
  ArrayContaining,
  Any,
  Anything,
  addCustomEqualityTesters,
  getObjectSubset
};

{
  "name": "sample-vitest-expect",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-vitest-expect",
      "version": "1.0.0",
      "dependencies": {
        "@vitest/expect": "2.1.9"
      }
    },
    "node_modules/@vitest/expect": {
      "version": "2.1.9",
      "resolved": "https://registry.npmjs.org/@vitest/expect/-/expect-2.1.9.tgz",
      "integrity": "sha512-UJCIkTBenHeKT1TTlKMJWy1laZewsRIzYighyYiJKZreqtdxSos/S1t+ktRMQWu2CKqaarrkeszJx1cgC5tGZw==",
      "license": "MIT",
      "dependencies": {
        "@vitest/spy": "2.1.9",
        "@vitest/utils": "2.1.9",
        "chai": "^5.1.2",
        "tinyrainbow": "^1.2.0"
      },
      "funding": {
        "url": "https://opencollective.com/vitest"
      }
    },
    "node_modules/@vitest/pretty-format": {
      "version": "2.1.9",
      "resolved": "https://registry.npmjs.org/@vitest/pretty-format/-/pretty-format-2.1.9.tgz",
      "integrity": "sha512-KhRIdGV2U9HOUzxfiHmY8IFHTdqtOhIzCpd8WRdJiE7D/HUcZVD0EgQCVjm+Q9gkUXWgBvMmTtZgIG48wq7sOQ==",
      "license": "MIT",
      "dependencies": {
        "tinyrainbow": "^1.2.0"
      },
      "funding": {
        "url": "https://opencollective.com/vitest"
      }
    },
    "node_modules/@vitest/spy": {
      "version": "2.1.9",
      "resolved": "https://registry.npmjs.org/@vitest/spy/-/spy-2.1.9.tgz",
      "integrity": "sha512-E1B35FwzXXTs9FHNK6bDszs7mtydNi5MIfUWpceJ8Xbfb1gBMscAnwLbEu+B44ed6W3XjL9/ehLPHR1fkf1KLQ==",
      "license": "MIT",
      "dependencies": {
        "tinyspy": "^3.0.2"
      },
      "funding": {
        "url": "https://opencollective.com/vitest"
      }
    },
    "node_modules/@vitest/utils": {
      "version": "2.1.9",
      "resolved": "https://registry.npmjs.org/@vitest/utils/-/utils-2.1.9.tgz",
      "integrity": "sha512-v0psaMSkNJ3A2NMrUEHFRzJtDPFn+/VWZ5WxImB21T9fjucJRmS7xCS3ppEnARb9y11OAzaD+P2Ps+b+BGX5iQ==",
      "license": "MIT",
      "dependencies": {
        "@vitest/pretty-format": "2.1.9",
        "loupe": "^3.1.2",
        "tinyrainbow": "^1.2.0"
      },
      "funding": {
        "url": "https://opencollective.com/vitest"
      }
    },
    "node_modules/assertion-error": {
      "version": "2.0.1",
      "resolved": "https://registry.npmjs.org/assertion-error/-/assertion-error-2.0.1.tgz",
      "integrity": "sha512-Izi8RQcffqCeNVgFigKli1ssklIbpHnCYc6AknXGYoB6grJqyeby7jv12JUQgmTAnIDnbck1uxksT4dzN3PWBA==",
      "license": "MIT",
      "engines": {
        "node": ">=12"
      }
    },
    "node_modules/chai": {
      "version": "5.3.3",
      "resolved": "https://registry.npmjs.org/chai/-/chai-5.3.3.tgz",
      "integrity": "sha512-4zNhdJD/iOjSH0A05ea+Ke6MU5mmpQcbQsSOkgdaUMJ9zTlDTD/GYlwohmIE2u0gaxHYiVHEn1Fw9mZ/ktJWgw==",
      "license": "MIT",
      "dependencies": {
        "assertion-error": "^2.0.1",
        "check-error": "^2.1.1",
        "deep-eql": "^5.0.1",
        "loupe": "^3.1.0",
        "pathval": "^2.0.0"
      },
      "engines": {
        "node": ">=18"
      }
    },
    "node_modules/check-error": {
      "version": "2.1.3",
      "resolved": "https://registry.npmjs.org/check-error/-/check-error-2.1.3.tgz",
      "integrity": "sha512-PAJdDJusoxnwm1VwW07VWwUN1sl7smmC3OKggvndJFadxxDRyFJBX/ggnu/KE4kQAB7a3Dp8f/YXC1FlUprWmA==",
      "license": "MIT",
      "engines": {
        "node": ">= 16"
      }
    },
    "node_modules/deep-eql": {
      "version": "5.0.2",
      "resolved": "https://registry.npmjs.org/deep-eql/-/deep-eql-5.0.2.tgz",
      "integrity": "sha512-h5k/5U50IJJFpzfL6nO9jaaumfjO/f2NjK/oYB2Djzm4p9L+3T9qWpZqZ2hAbLPuuYq9wrU08WQyBTL5GbPk5Q==",
      "license": "MIT",
      "engines": {
        "node": ">=6"
      }
    },
    "node_modules/loupe": {
      "version": "3.2.1",
      "resolved": "https://registry.npmjs.org/loupe/-/loupe-3.2.1.tgz",
      "integrity": "sha512-CdzqowRJCeLU72bHvWqwRBBlLcMEtIvGrlvef74kMnV2AolS9Y8xUv1I0U/MNAWMhBlKIoyuEgoJ0t/bbwHbLQ==",
      "license": "MIT"
    },
    "node_modules/pathval": {
      "version": "2.0.1",
      "resolved": "https://registry.npmjs.org/pathval/-/pathval-2.0.1.tgz",
      "integrity": "sha512-//nshmD55c46FuFw26xV/xFAaB5HF9Xdap7HJBBnrKdAd6/GxDBaNA1870O79+9ueg61cZLSVc+OaFlfmObYVQ==",
      "license": "MIT",
      "engines": {
        "node": ">= 14.16"
      }
    },
    "node_modules/tinyrainbow": {
      "version": "1.2.0",
      "resolved": "https://registry.npmjs.org/tinyrainbow/-/tinyrainbow-1.2.0.tgz",
      "integrity": "sha512-weEDEq7Z5eTHPDh4xjX789+fHfF+P8boiFB+0vbWzpbnbsEr/GRaohi/uMKxg8RZMXnl1ItAi/IUHWMsjDV7kQ==",
      "license": "MIT",
      "engines": {
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    "node_modules/tinyspy": {
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      "resolved": "https://registry.npmjs.org/tinyspy/-/tinyspy-3.0.2.tgz",
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      "license": "MIT",
      "engines": {
        "node": ">=14.0.0"
      }
    }
  }
}

{
  "name": "sample-vitest-expect",
  "version": "1.0.0",
  "description": "Clean-room verification sample for @vitest/expect",
  "type": "module",
  "main": "index.mjs",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "@vitest/expect": "2.1.9"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/%40vitest/expect@2.1.9",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40vitest/expect@2.1.9"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

import assert from 'node:assert/strict';
import {
  createExpect,
  expect,
  extendExpect,
  getState,
  setState,
  equals,
  isA,
  isAsymmetric,
  hasAsymmetric,
  StringContaining,
  StringMatching,
  ObjectContaining,
  ArrayContaining,
  Any,
  Anything
} from '../index.mjs';

// 1. createExpect configures Chai with JestChaiExpect, JestAsymmetricMatchers, and JestExtend
{
  const customExp = createExpect();
  assert.equal(typeof customExp, 'function');
  assert.equal(typeof customExp.extend, 'function');
  customExp(1 + 1).toBe(2);
}

// 2. toBe and toEqual perform primitive value and deep equality assertions
{
  expect(42).toBe(42);
  expect('hello world').toBe('hello world');
  expect(null).toBeNull();
  expect(undefined).toBeUndefined();
  expect(true).toBeTruthy();
  expect(false).toBeFalsy();
  expect(NaN).toBeNaN();

  const original = { a: 1, nested: { list: [10, 20] } };
  const duplicate = { a: 1, nested: { list: [10, 20] } };
  expect(original).toEqual(duplicate);
}

// 3. toMatchObject and toHaveProperty verify subset structures and nested object properties
{
  const payload = { id: 101, title: 'Report', details: { pages: 5, author: 'tester' } };
  expect(payload).toMatchObject({ id: 101, details: { pages: 5 } });
  expect(payload).toHaveProperty('details.author', 'tester');
}

// 4. toContain and toContainEqual assert element presence in arrays and strings
{
  expect([1, 2, 3]).toContain(2);
  expect([{ id: 1 }, { id: 2 }]).toContainEqual({ id: 1 });
  expect('vitest expect framework').toContain('expect');
  expect([1, 2, 3]).toHaveLength(3);
}

// 5. toBeGreaterThan, toBeLessThan, and toBeCloseTo validate numeric relationships and floating point values
{
  expect(10).toBeGreaterThan(5);
  expect(10).toBeGreaterThanOrEqual(10);
  expect(5).toBeLessThan(10);
  expect(5).toBeLessThanOrEqual(5);
  expect(0.1 + 0.2).toBeCloseTo(0.3, 5);
}

// 6. toBeTypeOf and toSatisfy evaluate type classifications and custom predicate functions
{
  expect('text').toBeTypeOf('string');
  expect(100).toBeTypeOf('number');
  expect(true).toBeTypeOf('boolean');
  expect(Symbol('sym')).toBeTypeOf('symbol');
  expect(25).toSatisfy(val => val > 20 && val < 30);
}

// 7. toThrow verifies exception throwing and error type matching
{
  expect(() => {
    throw new Error('invalid operation');
  }).toThrow('invalid operation');

  expect(() => {
    throw new TypeError('bad argument type');
  }).toThrow(TypeError);
}

// 8. Asymmetric matchers StringContaining, StringMatching, ObjectContaining, and ArrayContaining match partial values
{
  expect('prefix-order-123-suffix').toEqual(new StringContaining('order'));
  expect('order-9988').toEqual(new StringMatching(/^order-\d+$/));
  expect({ id: 1, role: 'admin', meta: { score: 95 } }).toEqual(
    new ObjectContaining({ role: 'admin', meta: new ObjectContaining({ score: 95 }) })
  );
  expect([1, 2, 3, 4]).toEqual(new ArrayContaining([2, 4]));
  expect('sample-text').toEqual(new Any(String));
  expect(42).toEqual(new Any(Number));
  expect({ custom: true }).toEqual(new Anything());
}

// 9. expect.extend registers custom matchers with custom pass and failure message logic
{
  extendExpect(expect, {
    toBeDivisibleBy(received, divisor) {
      const pass = received % divisor === 0;
      return {
        pass,
        message: () => `expected ${received} ${pass ? 'not ' : ''}to be divisible by ${divisor}`,
      };
    },
  });

  expect(15).toBeDivisibleBy(5);
  expect(14).not.toBeDivisibleBy(5);
}

// 10. getState and setState inspect and update matcher execution context
{
  setState({ testName: 'contract-suite', isRunning: true }, expect);
  const state = getState(expect);
  assert.equal(state.testName, 'contract-suite');
  assert.equal(state.isRunning, true);

  assert.equal(equals({ x: 1 }, { x: 1 }), true);
  assert.equal(equals({ x: 1 }, { x: 2 }), false);
  assert.equal(isA('String', 'abc'), true);
  assert.equal(isA('Number', 123), true);
  assert.equal(isAsymmetric(new Any(String)), true);
  assert.equal(hasAsymmetric({ matcher: new Any(Number) }), true);
}

console.log('All @vitest/expect contract assertions passed.');