pirates 4.0.7: addHook

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 pirates.addHook in pkg:npm/pirates@4.0.7
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/pirates@4.0.7
Demonstrate these symbols/APIs:
  - pirates.addHook

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:be1abcae5eca11736948e571587f261780b77f12353b7fb1518d973e2804c1b4","contract":["addHook transforms source code during CommonJS require execution","revert function restores original module loader and removes transformation","exts option allows adding require hooks for custom file extensions","matcher function selectively determines whether a file should be transformed","createReplacerHook utility correctly transforms targeted code and reverts","hook returning a non-string value throws an Error","passing a non-string extension throws a TypeError"],"goal":"verify pirates.addHook in pkg:npm/pirates@4.0.7","kind":"HOW","packages":["pkg:npm/pirates@4.0.7"],"schemaVersion":1,"symbols":["pirates.addHook"]},"contractCommand":["node","test/contract.js"],"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/pirates@4.0.7"],"schemaVersion":1,"subject":"pkg:npm/pirates@4.0.7","symbols":["pirates.addHook"],"verifierAdapter":"node-typescript@1"}

'use strict';

const { addHook } = require('pirates');

/**
 * Creates and registers a string replacement require hook.
 * @param {string|RegExp} pattern
 * @param {string} replacement
 * @param {object} [options]
 * @returns {() => void} revert function
 */
function createReplacerHook(pattern, replacement, options) {
  return addHook(
    (code) => code.replace(pattern, replacement),
    options
  );
}

module.exports = {
  addHook,
  createReplacerHook,
};

{
  "name": "sample-pirates",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-pirates",
      "version": "1.0.0",
      "dependencies": {
        "pirates": "4.0.7"
      }
    },
    "node_modules/pirates": {
      "version": "4.0.7",
      "resolved": "https://registry.npmjs.org/pirates/-/pirates-4.0.7.tgz",
      "integrity": "sha512-TfySrs/5nm8fQJDcBDuUng3VOUKsd7S+zqvbOTiGXHfxX4wK31ard+hoNuvkicM/2YFzlpDgABOevKSsB4G/FA==",
      "license": "MIT",
      "engines": {
        "node": ">= 6"
      }
    }
  }
}

{
  "name": "sample-pirates",
  "version": "1.0.0",
  "description": "Clean-room verification sample for pirates",
  "main": "index.js",
  "scripts": {
    "test": "node test/contract.js"
  },
  "dependencies": {
    "pirates": "4.0.7"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pirates.addHook in pkg:npm/pirates@4.0.7",
  "kind": "HOW",
  "packages": [
    "pkg:npm/pirates@4.0.7"
  ],
  "symbols": [
    "pirates.addHook"
  ]
}

const assert = require('node:assert/strict');
const path = require('node:path');
const { addHook, createReplacerHook } = require('../index.js');

const fixtureSample = path.join(__dirname, 'fixtures', 'sample.js');
const fixtureCustom = path.join(__dirname, 'fixtures', 'custom.ext');
const fixtureIgnored = path.join(__dirname, 'fixtures', 'ignored.js');

// 1. addHook transforms source code during CommonJS require execution
{
  const revert = addHook((code, filename) => {
    return code.replace('__GREETING__', 'HELLO_FROM_HOOK');
  });

  const result = require(fixtureSample);
  assert.equal(result.message, 'HELLO_FROM_HOOK');

  // 2. revert function restores original module loader and removes transformation
  revert();
  delete require.cache[require.resolve(fixtureSample)];

  const original = require(fixtureSample);
  assert.equal(original.message, '__GREETING__');
}

// 3. exts option allows adding require hooks for custom file extensions
{
  const revert = addHook((code, filename) => {
    return code.replace('CUSTOM_RAW_CONTENT', 'PARSED_CUSTOM_CONTENT');
  }, { exts: ['.ext'] });

  const custom = require(fixtureCustom);
  assert.equal(custom.content, 'PARSED_CUSTOM_CONTENT');

  revert();
  delete require.cache[require.resolve(fixtureCustom)];
}

// 4. matcher function selectively determines whether a file should be transformed
{
  const revert = addHook((code, filename) => {
    return 'module.exports = { message: "MATCHED_ONLY" };';
  }, {
    matcher: (filename) => filename.endsWith('sample.js')
  });

  delete require.cache[require.resolve(fixtureSample)];
  delete require.cache[require.resolve(fixtureIgnored)];

  const matched = require(fixtureSample);
  assert.equal(matched.message, 'MATCHED_ONLY');

  const ignored = require(fixtureIgnored);
  assert.equal(ignored.message, 'IGNORED_FILE');

  revert();
  delete require.cache[require.resolve(fixtureSample)];
  delete require.cache[require.resolve(fixtureIgnored)];
}

// 5. createReplacerHook utility correctly transforms targeted code and reverts
{
  const revert = createReplacerHook('__GREETING__', 'UTILITY_TRANSFORMED');

  delete require.cache[require.resolve(fixtureSample)];
  const transformed = require(fixtureSample);
  assert.equal(transformed.message, 'UTILITY_TRANSFORMED');

  revert();
  delete require.cache[require.resolve(fixtureSample)];
  const restored = require(fixtureSample);
  assert.equal(restored.message, '__GREETING__');
}

// 6. hook returning a non-string value throws an Error
{
  const revert = addHook((code, filename) => {
    return 12345; // non-string return value
  });

  delete require.cache[require.resolve(fixtureSample)];
  assert.throws(
    () => {
      require(fixtureSample);
    },
    (err) => {
      return err instanceof Error && err.message.includes('[Pirates] A hook returned a non-string');
    }
  );

  revert();
  delete require.cache[require.resolve(fixtureSample)];
}

// 7. passing a non-string extension throws a TypeError
{
  assert.throws(
    () => {
      addHook(() => {}, { exts: [42] });
    },
    {
      name: 'TypeError',
      message: 'Invalid Extension: 42'
    }
  );
}

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

module.exports = {
  content: 'CUSTOM_RAW_CONTENT'
};

module.exports = {
  message: 'IGNORED_FILE'
};

module.exports = {
  message: '__GREETING__'
};