@vitest/utils 4.1.10: createDefer

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/utils.createDefer in pkg:npm/%40vitest/utils@4.1.10
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40vitest/utils@4.1.10
Demonstrate these symbols/APIs:
  - @vitest/utils.createDefer

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:sha256:16b1b329549c4ecbfea08be8825c36ede0c161ecfcc0ef3d5064b6dd78154ca7","contract":["createDefer returns a Promise instance with attached resolve and reject functions","createDefer fulfills with the resolved value when resolve is called","createDefer rejects with the error when reject is called","createDefer supports promise chaining directly on the returned defer object"],"goal":"verify @vitest/utils.createDefer in pkg:npm/%40vitest/utils@4.1.10","kind":"HOW","packages":["pkg:npm/%40vitest/utils@4.1.10"],"schemaVersion":1,"symbols":["@vitest/utils.createDefer"]},"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/%40vitest/utils@4.1.10"],"schemaVersion":1,"subject":"pkg:npm/%40vitest/utils@4.1.10","symbols":["@vitest/utils.createDefer"],"verifierAdapter":"node-typescript@1"}

import { createDefer } from '@vitest/utils/helpers';

export { createDefer };

export function createDeferredTask() {
  const defer = createDefer();
  return {
    defer,
    resolve: (value) => defer.resolve(value),
    reject: (error) => defer.reject(error),
    wait: () => defer,
  };
}

{
  "name": "sample-vitest-utils-createdefer",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-vitest-utils-createdefer",
      "version": "1.0.0",
      "dependencies": {
        "@vitest/utils": "4.1.10"
      }
    },
    "node_modules/@vitest/pretty-format": {
      "version": "4.1.10",
      "resolved": "https://registry.npmjs.org/@vitest/pretty-format/-/pretty-format-4.1.10.tgz",
      "integrity": "sha512-W1HsjSH4MXQ9YfmmhLAoIYf1HRfekQCGngeIgcei6MP5QQGWUe0gkopdZQaVCFO+JDJMrAJGwa5pRpNpvy4P8Q==",
      "license": "MIT",
      "dependencies": {
        "tinyrainbow": "^3.1.0"
      },
      "funding": {
        "url": "https://opencollective.com/vitest"
      }
    },
    "node_modules/@vitest/utils": {
      "version": "4.1.10",
      "resolved": "https://registry.npmjs.org/@vitest/utils/-/utils-4.1.10.tgz",
      "integrity": "sha512-fy9am/HWxbaGt/Sawrp90vt6Y6jQwf1RX77cz3uwoJwJVMli/e1IEwRPnMNJ7vKfPTwo0diXifkpPvwH9v7nGA==",
      "license": "MIT",
      "dependencies": {
        "@vitest/pretty-format": "4.1.10",
        "convert-source-map": "^2.0.0",
        "tinyrainbow": "^3.1.0"
      },
      "funding": {
        "url": "https://opencollective.com/vitest"
      }
    },
    "node_modules/convert-source-map": {
      "version": "2.0.0",
      "resolved": "https://registry.npmjs.org/convert-source-map/-/convert-source-map-2.0.0.tgz",
      "integrity": "sha512-Kvp459HrV2FEJ1CAsi1Ku+MY3kasH19TFykTz2xWmMeq6bk2NU3XXvfJ+Q61m0xktWwt+1HSYf3JZsTms3aRJg==",
      "license": "MIT"
    },
    "node_modules/tinyrainbow": {
      "version": "3.1.1",
      "resolved": "https://registry.npmjs.org/tinyrainbow/-/tinyrainbow-3.1.1.tgz",
      "integrity": "sha512-yau8yJdTt989Mm0Bd/236QnzEiPf2xLLTqUZRUJOo/3CB078LSwzei343DgtJVmfJKJE3TMINY1u42SQsP6mXw==",
      "license": "MIT",
      "engines": {
        "node": ">=14.0.0"
      }
    }
  }
}

{
  "name": "sample-vitest-utils-createdefer",
  "version": "1.0.0",
  "type": "module",
  "main": "index.mjs",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "@vitest/utils": "4.1.10"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify @vitest/utils.createDefer in pkg:npm/%40vitest/utils@4.1.10",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40vitest/utils@4.1.10"
  ],
  "symbols": [
    "@vitest/utils.createDefer"
  ]
}

import assert from 'node:assert/strict';
import { createDefer } from '@vitest/utils/helpers';
import { createDeferredTask } from '../index.mjs';

// 1. createDefer returns a Promise instance with attached resolve and reject functions
{
  const defer = createDefer();
  assert.ok(defer instanceof Promise, 'defer must be an instance of Promise');
  assert.equal(typeof defer.resolve, 'function', 'defer must have a resolve method');
  assert.equal(typeof defer.reject, 'function', 'defer must have a reject method');
  defer.resolve();
  await defer;
}

// 2. createDefer fulfills with the resolved value when resolve is called
{
  const defer = createDefer();
  defer.resolve('test-value');
  const result = await defer;
  assert.equal(result, 'test-value');

  const task = createDeferredTask();
  task.resolve(100);
  const taskResult = await task.wait();
  assert.equal(taskResult, 100);
}

// 3. createDefer rejects with the error when reject is called
{
  const defer = createDefer();
  const testError = new Error('defer-error');
  defer.reject(testError);
  await assert.rejects(async () => {
    await defer;
  }, {
    name: 'Error',
    message: 'defer-error',
  });

  const task = createDeferredTask();
  task.reject(new Error('task-failed'));
  await assert.rejects(async () => {
    await task.wait();
  }, {
    name: 'Error',
    message: 'task-failed',
  });
}

// 4. createDefer supports promise chaining directly on the returned defer object
{
  const defer = createDefer();
  let finallyExecuted = false;
  const chained = defer
    .then((val) => val * 2)
    .finally(() => {
      finallyExecuted = true;
    });

  defer.resolve(21);
  const chainedResult = await chained;
  assert.equal(chainedResult, 42);
  assert.equal(finallyExecuted, true);
}