jest-util 30.4.1: pluralize

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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 jest-util.pluralize in pkg:npm/jest-util@30.4.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/jest-util@30.4.1
Demonstrate these symbols/APIs:
  - jest-util.pluralize

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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import { pluralize } from 'jest-util';

export { pluralize };

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  "dependencies": {
    "jest-util": "30.4.1"
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}

import assert from 'node:assert/strict';
import { pluralize } from '../index.mjs';

// 1. pluralize formats singular count with word unmodified when count is 1
{
  assert.strictEqual(pluralize('apple', 1), '1 apple');
  assert.strictEqual(pluralize('item', 1), '1 item');
}

// 2. pluralize appends default 's' ending for plural counts greater than 1
{
  assert.strictEqual(pluralize('apple', 2), '2 apples');
  assert.strictEqual(pluralize('item', 5), '5 items');
  assert.strictEqual(pluralize('test', 100), '100 tests');
}

// 3. pluralize appends default 's' ending for count of zero
{
  assert.strictEqual(pluralize('apple', 0), '0 apples');
  assert.strictEqual(pluralize('item', 0), '0 items');
}

// 4. pluralize appends default 's' ending for negative count values
{
  assert.strictEqual(pluralize('apple', -1), '-1 apples');
  assert.strictEqual(pluralize('item', -3), '-3 items');
}

// 5. pluralize applies custom ending when count is not 1
{
  assert.strictEqual(pluralize('box', 0, 'es'), '0 boxes');
  assert.strictEqual(pluralize('box', 2, 'es'), '2 boxes');
  assert.strictEqual(pluralize('class', 5, 'es'), '5 classes');
}

// 6. pluralize leaves word unmodified with custom ending when count is 1
{
  assert.strictEqual(pluralize('box', 1, 'es'), '1 box');
  assert.strictEqual(pluralize('class', 1, 'es'), '1 class');
}

console.log('All jest-util pluralize contract assertions passed successfully.');