util-deprecate 1.0.2: deprecate

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/util-deprecate@1.0.2
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/util-deprecate@1.0.2
Demonstrate these symbols/APIs:
  - deprecate

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:sha256:25c66795e5dcbdbc5fdb3c4ab08a0154cdb2f9d900adee29da239fd235e96b12","contract":["deprecate(fn, message) returns a wrapped function","wrapped function executes original function and returns its result","wrapped function preserves arguments and this context","invoking wrapped function emits a deprecation warning on first call","subsequent invocations of wrapped function do not emit duplicate warnings"],"goal":"verify pkg:npm/util-deprecate@1.0.2","kind":"HOW","packages":["pkg:npm/util-deprecate@1.0.2"],"schemaVersion":1,"symbols":["deprecate"]},"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/util-deprecate@1.0.2"],"schemaVersion":1,"subject":"pkg:npm/util-deprecate@1.0.2","symbols":["deprecate"],"verifierAdapter":"node-typescript@1"}

import deprecate from 'util-deprecate';

export function createDeprecatedCalculator() {
  return {
    multiplier: 2,
    double: deprecate(function (x) {
      return this.multiplier * x;
    }, 'double() is deprecated; use direct multiplication instead')
  };
}

export default deprecate;

{
  "name": "sample-util-deprecate",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-util-deprecate",
      "version": "1.0.0",
      "dependencies": {
        "util-deprecate": "1.0.2"
      }
    },
    "node_modules/util-deprecate": {
      "version": "1.0.2",
      "resolved": "https://registry.npmjs.org/util-deprecate/-/util-deprecate-1.0.2.tgz",
      "integrity": "sha512-EPD5q1uXyFxJpCrLnCc1nHnq3gOa6DZBocAIiI2TaSCA7VCJ1UJDMagCzIkXNsUYfD1daK//LTEQ8xiIbrHtcw==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-util-deprecate",
  "version": "1.0.0",
  "type": "module",
  "main": "index.mjs",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "util-deprecate": "1.0.2"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/util-deprecate@1.0.2",
  "kind": "HOW",
  "packages": [
    "pkg:npm/util-deprecate@1.0.2"
  ],
  "symbols": [
    "deprecate"
  ]
}

import assert from 'node:assert/strict';
import deprecate from 'util-deprecate';
import { createDeprecatedCalculator } from '../index.mjs';

const warnings = [];
process.on('warning', (warning) => {
  if (warning.name === 'DeprecationWarning') {
    warnings.push(warning.message);
  }
});

// 1. deprecate wraps a function and returns a new function
function add(a, b) {
  return a + b;
}
const deprecatedAdd = deprecate(add, 'add() is deprecated');
assert.equal(typeof deprecatedAdd, 'function', 'deprecate should return a function');

// 2. Wrapped function executes original function and returns its result
const sum = deprecatedAdd(3, 7);
assert.equal(sum, 10, 'deprecatedAdd(3, 7) should return 10');

// 3. Wrapped function preserves arguments and this context
const calc = createDeprecatedCalculator();
assert.equal(calc.double(5), 10, 'calc.double(5) should return 10 using this.multiplier');

// 4. Invoking wrapped function emits deprecation warning on first call only
const multiply = deprecate((x, y) => x * y, 'multiply() is deprecated');
const m1 = multiply(3, 4);
const m2 = multiply(5, 6);
assert.equal(m1, 12);
assert.equal(m2, 30);

// Wait for event loop tick to dispatch warnings
await new Promise((resolve) => setImmediate(resolve));

// Check warnings
const multiplyWarnings = warnings.filter((msg) => msg === 'multiply() is deprecated');
assert.equal(multiplyWarnings.length, 1, 'multiply() should emit exactly one deprecation warning despite multiple calls');

assert.ok(warnings.includes('add() is deprecated'), 'add() deprecation warning should be emitted');
assert.ok(warnings.includes('double() is deprecated; use direct multiplication instead'), 'calculator double() deprecation warning should be emitted');

console.log('All contract assertions passed.');