CodeSampleX

Sample

body-parser 1.20.3: urlencoded

Verified sample for npm body-parser 1.20.3: urlencoded. The contract ran on node 22 · linux debian/x64 · docker and passed: bodyParser.urlencoded parses…

sha256:f8f4a93fe91ec2813ab704e0478546c32d8035576e715bb089e5b132cfbe32d1

This network offers one thing: a sample that builds. It ran the sample in a sandbox and kept the signed receipt. It grades nothing and warrants nothing — whether the same code builds where you are is not something it measured. How many distinct signing keys filed a passing contract receipt. One is the author alone; more than one means somebody else built it too. A key is self-generated with nothing registered behind it, so it counts keys, not people. MIT-0

Execution evidence

The declared environment and the signed runs are kept apart, so you can see exactly what this sample ran and where.

Evidence basis
Signed contract pass
Verification receipts
1
Signing keys that built it
1
Declared environment linux 24 · ubuntu · glibc 2.39 x64 npm

Verification-run environments

Environment Contract Stages Run
node 22 · linux debian/x64 · docker ed25519:c1973797be207ac4 PASS compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS
CONTAINER_RUN · node-typescript@1node:22@sha256:8a34c4ab3ea2…		 2026-09-20

Case

HOW
Goal
verify body-parser.urlencoded in pkg:npm/body-parser@1.20.3
Packages
Symbols
  • body-parser.urlencoded
Created
2026-09-20T21:40:22Z

Contract

  1. bodyParser.urlencoded parses basic key-value pairs with extended false
  2. bodyParser.urlencoded with extended true parses nested object structures
  3. bodyParser.urlencoded rejects body exceeding limit with 413
  4. bodyParser.urlencoded rejects body exceeding parameterLimit with 413
  5. bodyParser.urlencoded verify option receives raw Buffer
  6. bodyParser.urlencoded ignores non-matching Content-Type and leaves body empty object

Files

  • PROMPT.md
  • csx.json
  • package-lock.json
  • package.json
  • spec.json
  • src/index.mjs
  • test/contract.mjs

Download the source artifact (tar.gz)

Source

PROMPT.md
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 body-parser.urlencoded in pkg:npm/body-parser@1.20.3
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/body-parser@1.20.3
Demonstrate these symbols/APIs:
  - body-parser.urlencoded

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.
csx.json
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package-lock.json
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package.json
{
  "name": "sample-body-parser-urlencoded",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "dependencies": {
    "body-parser": "1.20.3"
  }
}
spec.json
{
  "schemaVersion": 1,
  "goal": "verify body-parser.urlencoded in pkg:npm/body-parser@1.20.3",
  "kind": "HOW",
  "packages": [
    "pkg:npm/body-parser@1.20.3"
  ],
  "symbols": [
    "body-parser.urlencoded"
  ]
}
src/index.mjs
import bodyParser from 'body-parser';

export const urlencoded = bodyParser.urlencoded;
export { bodyParser };

/**
 * Execute body-parser urlencoded middleware against a request stream.
 * @param {Function} middleware - Middleware returned by bodyParser.urlencoded()
 * @param {object} req - Request stream or mock request
 * @param {object} [res={}] - Response object
 * @returns {Promise<any>} Resolves with req.body
 */
export function runMiddleware(middleware, req, res = {}) {
  return new Promise((resolve, reject) => {
    middleware(req, res, (err) => {
      if (err) {
        return reject(err);
      }
      resolve(req.body);
    });
  });
}

export default urlencoded;
test/contract.mjs
import assert from 'node:assert';
import { Readable } from 'node:stream';
import { urlencoded, runMiddleware } from '../src/index.mjs';

function createMockReq(bodyContent, contentType = 'application/x-www-form-urlencoded') {
  const req = new Readable({
    read() {
      if (bodyContent !== undefined && bodyContent !== null) {
        this.push(bodyContent);
      }
      this.push(null);
    }
  });
  const length = bodyContent ? Buffer.byteLength(bodyContent) : 0;
  req.headers = {
    'content-type': contentType,
    'content-length': length.toString()
  };
  return req;
}

// 1. bodyParser.urlencoded parses basic key-value pairs with extended false
{
  const parser = urlencoded({ extended: false });
  const req = createMockReq('user=alice&status=active');
  const body = await runMiddleware(parser, req);
  assert.strictEqual(body.user, 'alice');
  assert.strictEqual(body.status, 'active');
  assert.strictEqual(Object.keys(body).length, 2);
  assert.strictEqual(req.body.user, 'alice');
}

// 2. bodyParser.urlencoded with extended true parses nested object structures
{
  const parser = urlencoded({ extended: true });
  const req = createMockReq('profile%5Bname%5D=bob&profile%5Brole%5D=developer');
  const body = await runMiddleware(parser, req);
  assert.strictEqual(body.profile.name, 'bob');
  assert.strictEqual(body.profile.role, 'developer');
  assert.strictEqual(Object.keys(body.profile).length, 2);
  assert.strictEqual(req.body.profile.name, 'bob');
}

// 3. bodyParser.urlencoded rejects body exceeding limit with 413
{
  const parser = urlencoded({ extended: false, limit: 10 });
  const req = createMockReq('key=value_exceeding_ten_bytes');
  await assert.rejects(
    async () => {
      await runMiddleware(parser, req);
    },
    (err) => {
      assert.strictEqual(err.status, 413);
      assert.strictEqual(err.type, 'entity.too.large');
      return true;
    }
  );
}

// 4. bodyParser.urlencoded rejects body exceeding parameterLimit with 413
{
  const parser = urlencoded({ extended: false, parameterLimit: 2 });
  const req = createMockReq('a=1&b=2&c=3');
  await assert.rejects(
    async () => {
      await runMiddleware(parser, req);
    },
    (err) => {
      assert.strictEqual(err.status, 413);
      assert.strictEqual(err.type, 'parameters.too.many');
      return true;
    }
  );
}

// 5. bodyParser.urlencoded verify option receives raw Buffer
{
  let capturedBuf = null;
  let capturedEncoding = null;
  const parser = urlencoded({
    extended: false,
    verify: (req, res, buf, encoding) => {
      capturedBuf = buf;
      capturedEncoding = encoding;
    }
  });
  const rawPayload = 'user=charlie&role=tester';
  const req = createMockReq(rawPayload);
  const body = await runMiddleware(parser, req);
  assert.strictEqual(body.user, 'charlie');
  assert.strictEqual(body.role, 'tester');
  assert(Buffer.isBuffer(capturedBuf));
  assert.strictEqual(capturedBuf.toString('utf8'), rawPayload);
  assert.strictEqual(capturedEncoding, 'utf-8');
}

// 6. bodyParser.urlencoded ignores non-matching Content-Type and leaves body empty object
{
  const parser = urlencoded({ extended: false });
  const req = createMockReq('{"not":"urlencoded"}', 'application/json');
  const body = await runMiddleware(parser, req);
  assert.deepStrictEqual(body, {});
  assert.deepStrictEqual(req.body, {});
}

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

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