pkce-challenge 5.0.1: generateChallenge

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 pkce-challenge.generateChallenge in pkg:npm/pkce-challenge@5.0.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/pkce-challenge@5.0.1
Demonstrate these symbols/APIs:
  - pkce-challenge.generateChallenge

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:sha256:3c4645b1d02b3434312331f2fd047d9227c2d4be0269222bedb91065ce9b5b1e","contract":["generateChallenge computes the matching base64url sha256 challenge for a given code_verifier","generateChallenge produces RFC 7636 Appendix B test vector challenge for the reference verifier","generateChallenge produces a 43-character base64url challenge string without padding","generateChallenge produces identical challenges for identical verifier strings","generateChallenge produces distinct challenges for distinct verifier strings","generateChallenge computes the correct challenge for a maximum length 128-character verifier"],"goal":"verify pkce-challenge.generateChallenge in pkg:npm/pkce-challenge@5.0.1","kind":"HOW","packages":["pkg:npm/pkce-challenge@5.0.1"],"schemaVersion":1,"symbols":["pkce-challenge.generateChallenge"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"esm","os":"linux","osVersionBucket":"24","packageManager":"npm","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/pkce-challenge@5.0.1"],"schemaVersion":1,"subject":"pkg:npm/pkce-challenge@5.0.1","symbols":["pkce-challenge.generateChallenge"],"verifierAdapter":"node-typescript@1"}

import { generateChallenge } from "pkce-challenge";

/**
 * Derives a PKCE code challenge from a given code verifier using SHA-256 and base64url encoding.
 *
 * @param {string} codeVerifier - The PKCE code verifier string.
 * @returns {Promise<string>} The base64url-encoded SHA-256 code challenge.
 */
export async function createChallenge(codeVerifier) {
  return await generateChallenge(codeVerifier);
}

export { generateChallenge };
export default generateChallenge;

{
  "name": "sample-pkce-challenge-generate-challenge",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-pkce-challenge-generate-challenge",
      "version": "1.0.0",
      "dependencies": {
        "pkce-challenge": "5.0.1"
      }
    },
    "node_modules/pkce-challenge": {
      "version": "5.0.1",
      "resolved": "https://registry.npmjs.org/pkce-challenge/-/pkce-challenge-5.0.1.tgz",
      "integrity": "sha512-wQ0b/W4Fr01qtpHlqSqspcj3EhBvimsdh0KlHhH8HRZnMsEa0ea2fTULOXOS9ccQr3om+GcGRk4e+isrZWV8qQ==",
      "license": "MIT",
      "engines": {
        "node": ">=16.20.0"
      }
    }
  }
}

{
  "name": "sample-pkce-challenge-generate-challenge",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "description": "Clean-room code sample for pkce-challenge.generateChallenge in pkce-challenge@5.0.1",
  "main": "index.js",
  "dependencies": {
    "pkce-challenge": "5.0.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkce-challenge.generateChallenge in pkg:npm/pkce-challenge@5.0.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/pkce-challenge@5.0.1"
  ],
  "symbols": [
    "pkce-challenge.generateChallenge"
  ]
}

import assert from "node:assert/strict";
import { createHash } from "node:crypto";
import { generateChallenge } from "pkce-challenge";

async function run() {
  // 1. generateChallenge computes the matching base64url sha256 challenge for a given code_verifier
  const verifier = "sample_verifier_string_for_pkce_contract_test_12345";
  const challenge = await generateChallenge(verifier);
  const expectedSha256Base64Url = createHash("sha256")
    .update(verifier)
    .digest("base64url");
  assert.equal(challenge, expectedSha256Base64Url);

  // 2. generateChallenge produces RFC 7636 Appendix B test vector challenge for the reference verifier
  const rfcVerifier = "dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk";
  const rfcExpectedChallenge = "E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM";
  const rfcChallenge = await generateChallenge(rfcVerifier);
  assert.equal(rfcChallenge, rfcExpectedChallenge);

  // 3. generateChallenge produces a 43-character base64url challenge string without padding
  assert.equal(challenge.length, 43);
  assert.equal(challenge.includes("="), false);
  assert.equal(challenge.includes("+"), false);
  assert.equal(challenge.includes("/"), false);
  assert.match(challenge, /^[A-Za-z0-9_-]{43}$/);

  // 4. generateChallenge produces identical challenges for identical verifier strings
  const challengeAgain = await generateChallenge(verifier);
  assert.equal(challengeAgain, challenge);

  // 5. generateChallenge produces distinct challenges for distinct verifier strings
  const otherVerifier = "another_sample_verifier_string_for_pkce_contract_test_67890";
  const otherChallenge = await generateChallenge(otherVerifier);
  assert.notEqual(otherChallenge, challenge);

  // 6. generateChallenge computes the correct challenge for a maximum length 128-character verifier
  const longVerifier = "a".repeat(128);
  const longChallenge = await generateChallenge(longVerifier);
  const expectedLongChallenge = createHash("sha256")
    .update(longVerifier)
    .digest("base64url");
  assert.equal(longChallenge, expectedLongChallenge);

  console.log("All pkce-challenge.generateChallenge contract checks passed.");
}

await run();