@vitest/utils 4.1.10: nanoid

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.nanoid 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.nanoid

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:sha256:8649e08249ee57825f23fe8e257aa911e83577dcef524648e6da5a85e368b4e7","contract":["nanoid generates a 21-character string by default using URL-safe characters","nanoid generates a string of custom length when size parameter is specified","nanoid returns an empty string when size is zero","nanoid produces unique identifiers across multiple consecutive invocations","nanoid generates strings composed exclusively of URL-safe alphabet characters"],"goal":"verify @vitest/utils.nanoid in pkg:npm/%40vitest/utils@4.1.10","kind":"HOW","packages":["pkg:npm/%40vitest/utils@4.1.10"],"schemaVersion":1,"symbols":["@vitest/utils.nanoid"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","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/utils@4.1.10"],"schemaVersion":1,"subject":"pkg:npm/%40vitest/utils@4.1.10","symbols":["@vitest/utils.nanoid"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-vitest-utils-nanoid",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-vitest-utils-nanoid",
      "version": "1.0.0",
      "license": "MIT-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-nanoid",
  "version": "1.0.0",
  "description": "Clean-room verification sample for @vitest/utils.nanoid",
  "type": "module",
  "main": "src/index.mjs",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "@vitest/utils": "4.1.10"
  }
}

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

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

/**
 * Generate a URL-safe unique identifier.
 *
 * @param {number} [size=21] - The length of the ID to generate
 * @returns {string} - The generated ID string
 */
export function generateId(size) {
  return nanoid(size);
}

/**
 * Generate a custom-prefixed unique identifier.
 *
 * @param {string} prefix - Prefix to prepend to the ID
 * @param {number} [size=21] - The length of the random portion
 * @returns {string} - Prefixed identifier string
 */
export function generatePrefixedId(prefix, size) {
  return `${prefix}_${nanoid(size)}`;
}

export { nanoid };
export default nanoid;

import assert from 'node:assert/strict';
import { nanoid } from '@vitest/utils/helpers';
import { generateId, generatePrefixedId } from '../src/index.mjs';

// 1. nanoid generates a 21-character string by default using URL-safe characters
{
  const id = nanoid();
  assert.equal(typeof id, 'string', 'nanoid() must return a string');
  assert.equal(id.length, 21, 'Default nanoid() length must be 21 characters');
  assert.match(id, /^[A-Za-z0-9_-]{21}$/, 'nanoid() output must match URL-safe alphabet');

  const wrapperId = generateId();
  assert.equal(typeof wrapperId, 'string');
  assert.equal(wrapperId.length, 21);
}

// 2. nanoid generates a string of custom length when size parameter is specified
{
  const lengths = [1, 5, 10, 16, 32, 64];
  for (const len of lengths) {
    const id = nanoid(len);
    assert.equal(id.length, len, `nanoid(${len}) must return a string of length ${len}`);
    assert.match(id, /^[A-Za-z0-9_-]+$/, 'Custom length nanoid must use URL-safe characters');
  }

  const customWrapperId = generateId(12);
  assert.equal(customWrapperId.length, 12);
}

// 3. nanoid returns an empty string when size is zero
{
  const empty = nanoid(0);
  assert.equal(empty, '', 'nanoid(0) must return an empty string');
}

// 4. nanoid produces unique identifiers across multiple consecutive invocations
{
  const count = 500;
  const set = new Set();
  for (let i = 0; i < count; i++) {
    set.add(nanoid());
  }
  assert.equal(set.size, count, `All ${count} generated IDs must be distinct`);
}

// 5. nanoid generates strings composed exclusively of URL-safe alphabet characters
{
  const urlSafePattern = /^[A-Za-z0-9_-]+$/;
  for (let i = 0; i < 50; i++) {
    const id = nanoid(24);
    assert.match(id, urlSafePattern, 'Generated ID must strictly contain only URL-safe characters');
  }

  const prefixed = generatePrefixedId('test', 16);
  assert.match(prefixed, /^test_[A-Za-z0-9_-]{16}$/, 'Prefixed ID must match expected prefix and format');
}

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