CodeSampleX

Sample

@babel/plugin-transform-arrow-functions 7.29.7

Verified sample for npm @babel/plugin-transform-arrow-functions 7.29.7. The contract ran on node 22 · linux alpine/x64 · docker and passed.

sha256:cc758228363ff03148c248866e238430eb24c6fadcf69abd6a965987e15283fc

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 alpine/x64 · docker ed25519:c1973797be207ac4 PASS compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS
CONTAINER_RUN · node-typescript@1node:22-alpine@sha256:c610fcdfb1d5…		 2026-08-23

Case

HOW
Goal
verify pkg:npm/%40babel/plugin-transform-arrow-functions@7.29.7
Packages
Created
2026-08-23T07:43:14Z

Contract

  1. Plugin default export is a function factory asserting Babel 7 compatibility
  2. Plugin factory returns an object named transform-arrow-functions with ArrowFunctionExpression visitor method
  3. ArrowFunctionExpression visitor invokes arrowFunctionToExpression with default loose options
  4. ArrowFunctionExpression visitor enables specCompliant and disables noNewArrows when spec option is true
  5. ArrowFunctionExpression visitor prioritizes noNewArrows compiler assumption over spec option
  6. ArrowFunctionExpression visitor skips transformation when node is not an arrow function expression
  7. Module helpers instantiate the plugin and execute arrow function transformations

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 pkg:npm/%40babel/plugin-transform-arrow-functions@7.29.7
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40babel/plugin-transform-arrow-functions@7.29.7

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": "verify-babel-plugin-transform-arrow-functions",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "@babel/plugin-transform-arrow-functions": "7.29.7"
  }
}
spec.json
{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/%40babel/plugin-transform-arrow-functions@7.29.7",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40babel/plugin-transform-arrow-functions@7.29.7"
  ]
}
src/index.mjs
import arrowFunctionsPlugin from '@babel/plugin-transform-arrow-functions';

/**
 * Creates and initializes the arrow-functions plugin instance.
 * @param {object} [api] - Optional Babel API object.
 * @param {object} [options] - Optional plugin options (e.g. { spec: true }).
 * @returns {object} Plugin instance object with name and visitor.
 */
export function createArrowFunctionsPlugin(api, options = {}) {
  const plugin = arrowFunctionsPlugin.default || arrowFunctionsPlugin;
  const babelApi = api || {
    assertVersion: (range) => Boolean(range),
    assumption: () => undefined
  };
  return plugin(babelApi, options);
}

/**
 * Transforms an ArrowFunctionExpression AST path using the arrow-functions visitor.
 * @param {object} pluginInstance - Plugin instance returned by createArrowFunctionsPlugin.
 * @param {object} path - Mock or real Babel AST path for ArrowFunctionExpression.
 */
export function applyArrowFunctionsTransform(pluginInstance, path) {
  if (pluginInstance.visitor && typeof pluginInstance.visitor.ArrowFunctionExpression === 'function') {
    pluginInstance.visitor.ArrowFunctionExpression(path);
  }
}
test/contract.mjs
import assert from 'node:assert/strict';
import arrowFunctionsPlugin from '@babel/plugin-transform-arrow-functions';
import { createArrowFunctionsPlugin, applyArrowFunctionsTransform } from '../src/index.mjs';

// 1. Verify default export is the plugin factory function and asserts Babel 7 compatibility
const plugin = arrowFunctionsPlugin.default || arrowFunctionsPlugin;
assert.equal(typeof plugin, 'function', 'Default export must be a plugin factory function');

let assertedVersion = null;
const mockApi = {
  assertVersion(version) {
    assertedVersion = version;
  },
  assumption(name) {
    return undefined;
  }
};
const instance = plugin(mockApi, {});
assert.equal(assertedVersion, 7, 'Plugin must assert Babel version 7 compatibility');

// 2. Verify plugin structure and visitor
assert.equal(typeof instance, 'object', 'Plugin factory must return an object');
assert.equal(instance.name, 'transform-arrow-functions', 'Plugin name must be transform-arrow-functions');
assert.equal(typeof instance.visitor, 'object', 'Plugin must provide a visitor object');
assert.equal(typeof instance.visitor.ArrowFunctionExpression, 'function', 'Visitor must provide ArrowFunctionExpression method');

// 3. Verify ArrowFunctionExpression visitor invokes arrowFunctionToExpression with default loose options
{
  let passedOpts = null;
  const mockPath = {
    isArrowFunctionExpression: () => true,
    arrowFunctionToExpression: (opts) => {
      passedOpts = opts;
    }
  };
  instance.visitor.ArrowFunctionExpression(mockPath);
  assert.deepEqual(passedOpts, {
    allowInsertArrow: false,
    noNewArrows: true,
    specCompliant: false
  }, 'Default visitor execution must invoke arrowFunctionToExpression with loose configuration');
}

// 4. Verify ArrowFunctionExpression visitor enables specCompliant and disables noNewArrows when spec option is true
{
  const specInstance = plugin(mockApi, { spec: true });
  let passedOpts = null;
  const mockPath = {
    isArrowFunctionExpression: () => true,
    arrowFunctionToExpression: (opts) => {
      passedOpts = opts;
    }
  };
  specInstance.visitor.ArrowFunctionExpression(mockPath);
  assert.deepEqual(passedOpts, {
    allowInsertArrow: false,
    noNewArrows: false,
    specCompliant: true
  }, 'spec option must configure specCompliant: true and noNewArrows: false');
}

// 5. Verify ArrowFunctionExpression visitor prioritizes noNewArrows compiler assumption over spec option
{
  const assumptionApi = {
    assertVersion: () => true,
    assumption: (name) => (name === 'noNewArrows' ? true : undefined)
  };
  const assumptionInstance = plugin(assumptionApi, { spec: true });
  let passedOpts = null;
  const mockPath = {
    isArrowFunctionExpression: () => true,
    arrowFunctionToExpression: (opts) => {
      passedOpts = opts;
    }
  };
  assumptionInstance.visitor.ArrowFunctionExpression(mockPath);
  assert.deepEqual(passedOpts, {
    allowInsertArrow: false,
    noNewArrows: true,
    specCompliant: false
  }, 'Compiler assumption noNewArrows: true must override spec: true');
}

// 6. Verify ArrowFunctionExpression visitor skips transformation when node is not an arrow function expression
{
  let called = false;
  const mockNonArrowPath = {
    isArrowFunctionExpression: () => false,
    arrowFunctionToExpression: () => {
      called = true;
    }
  };
  instance.visitor.ArrowFunctionExpression(mockNonArrowPath);
  assert.equal(called, false, 'Visitor must not invoke arrowFunctionToExpression if isArrowFunctionExpression returns false');
}

// 7. Verify module helpers instantiate the plugin and execute arrow function transformations
{
  const helperInstance = createArrowFunctionsPlugin();
  assert.equal(helperInstance.name, 'transform-arrow-functions');

  let passedOpts = null;
  const mockPath = {
    isArrowFunctionExpression: () => true,
    arrowFunctionToExpression: (opts) => {
      passedOpts = opts;
    }
  };
  applyArrowFunctionsTransform(helperInstance, mockPath);
  assert.deepEqual(passedOpts, {
    allowInsertArrow: false,
    noNewArrows: true,
    specCompliant: false
  }, 'Helper function must execute transformation with expected parameters');
}

console.log('Contract assertions passed.');

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