@vitest/expect 2.1.9: hasAsymmetric

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 @vitest/expect.hasAsymmetric in pkg:npm/%40vitest/expect@2.1.9
Kind: HOW

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

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:f60f7755215c794843a5fec5cde9f53426fd2be3cceec9b52772ffc05db838f0","contract":["assert hasAsymmetric returns false for primitive values, functions, and empty containers","assert hasAsymmetric returns true for top-level asymmetric matchers","assert hasAsymmetric detects nested asymmetric matchers inside objects, arrays, and Sets","assert hasAsymmetric handles circular object references safely without infinite recursion","assert hasAsymmetric detects custom objects that provide an asymmetricMatch method","assert hasAsymmetric skips re-evaluating objects already recorded in the seen Set parameter"],"goal":"verify @vitest/expect.hasAsymmetric in pkg:npm/%40vitest/expect@2.1.9","kind":"HOW","packages":["pkg:npm/%40vitest/expect@2.1.9"],"schemaVersion":1,"symbols":["@vitest/expect.hasAsymmetric"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"esm","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","symbols":["@vitest/expect.hasAsymmetric"],"verifierAdapter":"node-typescript@1"}

import { hasAsymmetric } from '@vitest/expect';

/**
 * Checks whether a given value or any nested property/element contains an asymmetric matcher.
 *
 * @param {unknown} value - Value or object tree to inspect.
 * @param {Set<unknown>} [seen] - Set tracking visited objects to prevent cycles.
 * @returns {boolean} True if an asymmetric matcher is present.
 */
export function containsAsymmetric(value, seen) {
  return hasAsymmetric(value, seen);
}

export { hasAsymmetric };

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{
  "name": "sample-vitest-expect-hasasymmetric",
  "version": "1.0.0",
  "description": "Clean-room verification sample for hasAsymmetric in @vitest/expect",
  "type": "module",
  "main": "index.mjs",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "license": "MIT-0",
  "dependencies": {
    "@vitest/expect": "2.1.9"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify @vitest/expect.hasAsymmetric in pkg:npm/%40vitest/expect@2.1.9",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40vitest/expect@2.1.9"
  ],
  "symbols": [
    "@vitest/expect.hasAsymmetric"
  ]
}

import assert from 'node:assert/strict';
import { hasAsymmetric, containsAsymmetric } from '../index.mjs';
import {
  Any,
  Anything,
  ArrayContaining,
  ObjectContaining,
  StringContaining,
  StringMatching
} from '@vitest/expect';

async function runContract() {
  // 1. assert hasAsymmetric returns false for primitive values, functions, and empty containers
  assert.strictEqual(hasAsymmetric(42), false);
  assert.strictEqual(hasAsymmetric('literal string'), false);
  assert.strictEqual(hasAsymmetric(true), false);
  assert.strictEqual(hasAsymmetric(false), false);
  assert.strictEqual(hasAsymmetric(null), false);
  assert.strictEqual(hasAsymmetric(undefined), false);
  assert.strictEqual(hasAsymmetric(Symbol('sym')), false);
  assert.strictEqual(hasAsymmetric(() => {}), false);
  assert.strictEqual(hasAsymmetric({}), false);
  assert.strictEqual(hasAsymmetric([]), false);
  assert.strictEqual(hasAsymmetric(new Set()), false);
  assert.strictEqual(hasAsymmetric({ a: 1, b: [2, 3], c: { d: 'test' } }), false);
  assert.strictEqual(containsAsymmetric('primitive'), false);

  // 2. assert hasAsymmetric returns true for top-level asymmetric matchers
  assert.strictEqual(hasAsymmetric(new Any(Number)), true);
  assert.strictEqual(hasAsymmetric(new Anything()), true);
  assert.strictEqual(hasAsymmetric(new ArrayContaining([1, 2])), true);
  assert.strictEqual(hasAsymmetric(new ObjectContaining({ key: 'val' })), true);
  assert.strictEqual(hasAsymmetric(new StringContaining('part')), true);
  assert.strictEqual(hasAsymmetric(new StringMatching(/^pattern$/)), true);
  assert.strictEqual(containsAsymmetric(new Anything()), true);

  // 3. assert hasAsymmetric detects nested asymmetric matchers inside objects, arrays, and Sets
  assert.strictEqual(
    hasAsymmetric({ user: { id: 10, name: new StringContaining('Alice') } }),
    true
  );
  assert.strictEqual(
    hasAsymmetric([1, [2, new Anything()]]),
    true
  );
  assert.strictEqual(
    hasAsymmetric(new Set([10, new ObjectContaining({ enabled: true })])),
    true
  );
  assert.strictEqual(
    hasAsymmetric({ items: new Set([new ArrayContaining([99])]) }),
    true
  );

  // 4. assert hasAsymmetric handles circular object references safely without infinite recursion
  const cyclicObj = { id: 1 };
  cyclicObj.self = cyclicObj;
  assert.strictEqual(hasAsymmetric(cyclicObj), false);

  const cyclicWithMatcher = { id: 2, meta: {} };
  cyclicWithMatcher.meta.root = cyclicWithMatcher;
  cyclicWithMatcher.meta.expected = new Any(String);
  assert.strictEqual(hasAsymmetric(cyclicWithMatcher), true);

  // 5. assert hasAsymmetric detects custom objects that provide an asymmetricMatch method
  const customMatcher = {
    asymmetricMatch(actual) {
      return typeof actual === 'number' && actual > 0;
    }
  };
  assert.strictEqual(hasAsymmetric(customMatcher), true);
  assert.strictEqual(hasAsymmetric({ rule: customMatcher }), true);
  assert.strictEqual(hasAsymmetric([customMatcher]), true);

  const nonMatcherObject = {
    asymmetricMatch: 'not-a-function'
  };
  assert.strictEqual(hasAsymmetric(nonMatcherObject), false);

  // 6. assert hasAsymmetric skips re-evaluating objects already recorded in the seen Set parameter
  const targetWithMatcher = { matcher: new Anything() };
  assert.strictEqual(hasAsymmetric(targetWithMatcher), true);

  const prePopulatedSeen = new Set([targetWithMatcher]);
  assert.strictEqual(hasAsymmetric(targetWithMatcher, prePopulatedSeen), false);

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

runContract().catch((err) => {
  console.error('Contract test failed:', err);
  process.exit(1);
});