CodeSampleX

Sample

body-parser 1.20.3: json

Verified sample for npm body-parser 1.20.3: json. The contract ran on node 22 · linux debian/x64 · docker and passed: json parses valid JSON body into an…

sha256:397831963716b88813865d4f8c9578dab1a9e91763d36feea32ad40205cc98cb

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…		 2026-09-19

Case

HOW
Goal
verify json in pkg:npm/body-parser@1.20.3
Packages
Symbols
  • json
Created
2026-09-18T22:50:31Z

Contract

  1. json parses valid JSON body into an object
  2. json rejects malformed JSON with 400 status code
  3. json rejects payload exceeding byte limit with 413 status code
  4. json supports custom reviver function
  5. json verify option receives raw buffer
  6. json strict mode rejects primitive JSON values

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 json 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:
  - json

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

export const json = bodyParser.json;

export function parseJson(options) {
  const middleware = json(options);
  return (req, res = {}) =>
    new Promise((resolve, reject) => {
      middleware(req, res, (err) => {
        if (err) {
          reject(err);
        } else {
          resolve(req.body);
        }
      });
    });
}

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

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

// 1. json parses valid JSON body into an object
{
  const parse = parseJson();
  const req = createRequest(JSON.stringify({ status: 'ok', value: 42 }));
  const result = await parse(req);
  assert.deepStrictEqual(result, { status: 'ok', value: 42 });
  assert.deepStrictEqual(req.body, { status: 'ok', value: 42 });
}

// 2. json rejects malformed JSON with 400 status code
{
  const parse = parseJson();
  const req = createRequest('{"unclosed": "json');
  await assert.rejects(
    async () => {
      await parse(req);
    },
    (err) => {
      assert.strictEqual(err.status, 400);
      assert.strictEqual(err.type, 'entity.parse.failed');
      return true;
    }
  );
}

// 3. json rejects payload exceeding byte limit with 413 status code
{
  const parse = parseJson({ limit: 16 });
  const req = createRequest(JSON.stringify({ message: 'payload that definitely exceeds sixteen bytes' }));
  await assert.rejects(
    async () => {
      await parse(req);
    },
    (err) => {
      assert.strictEqual(err.status, 413);
      assert.strictEqual(err.type, 'entity.too.large');
      return true;
    }
  );
}

// 4. json supports custom reviver function
{
  const parse = parseJson({
    reviver: (key, val) => (typeof val === 'number' ? val * 2 : val)
  });
  const req = createRequest(JSON.stringify({ count: 21 }));
  const result = await parse(req);
  assert.strictEqual(result.count, 42);
}

// 5. json verify option receives raw buffer
{
  let capturedBuf = null;
  const parse = parseJson({
    verify: (req, res, buf) => {
      capturedBuf = buf;
    }
  });
  const rawPayload = JSON.stringify({ verified: true });
  const req = createRequest(rawPayload);
  const result = await parse(req);
  assert.deepStrictEqual(result, { verified: true });
  assert(Buffer.isBuffer(capturedBuf));
  assert.strictEqual(capturedBuf.toString('utf8'), rawPayload);
}

// 6. json strict mode rejects primitive JSON values
{
  const parse = parseJson({ strict: true });
  const req = createRequest('"just a string"');
  await assert.rejects(
    async () => {
      await parse(req);
    },
    (err) => {
      assert.strictEqual(err.status, 400);
      assert.strictEqual(err.type, 'entity.parse.failed');
      return true;
    }
  );
}

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

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