CodeSampleX

Sample

@babel/plugin-transform-duplicate-keys 8.0.1

Verified sample for npm @babel/plugin-transform-duplicate-keys 8.0.1. The contract ran on node 22 · linux alpine/x64 · docker and passed.

sha256:787c1570fc7ed0208a43db0520c6ae961e3ad2747e57ba9be5b02c893add9173

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@1		 2026-08-20

Case

HOW
Goal
verify pkg:npm/%40babel/plugin-transform-duplicate-keys@8.0.1
Packages
Created
2026-08-20T17:46:23Z

Contract

  1. assert @babel/plugin-transform-duplicate-keys exports a Babel plugin factory function
  2. assert duplicate identifier keys in object literals are transformed to computed string property keys
  3. assert duplicate string literal keys and matching identifier keys are transformed to computed keys
  4. assert duplicate numeric literal keys and matching string keys are normalized and transformed to computed keys
  5. assert getter and setter properties with duplicate keys are transformed into computed getters or properties
  6. assert multiple successive duplicate keys in object literals and nested objects are all transformed into computed keys
  7. assert non-duplicate object properties remain untransformed standard properties

Files

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

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-duplicate-keys@8.0.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40babel/plugin-transform-duplicate-keys@8.0.1

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-babel-plugin-transform-duplicate-keys",
  "version": "1.0.0",
  "private": true,
  "description": "Clean-room verification sample for @babel/plugin-transform-duplicate-keys",
  "main": "src/index.js",
  "scripts": {
    "test": "node test/contract.js"
  },
  "dependencies": {
    "@babel/plugin-transform-duplicate-keys": "8.0.1"
  },
  "license": "MIT-0"
}
spec.json
{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/%40babel/plugin-transform-duplicate-keys@8.0.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40babel/plugin-transform-duplicate-keys@8.0.1"
  ]
}
src/index.js
'use strict';

const transformDuplicateKeys = require('@babel/plugin-transform-duplicate-keys');
const babel = require('@babel/core');

/**
 * Transforms JavaScript code using the duplicate-keys transform plugin.
 *
 * @param {string} sourceCode - The input JavaScript source code.
 * @param {object} [options] - Options passed to the plugin.
 * @returns {string} The transformed JavaScript code.
 */
function transformDuplicateKeysCode(sourceCode, options = {}) {
  const result = babel.transformSync(sourceCode, {
    plugins: [[transformDuplicateKeys, options]],
    configFile: false,
    babelrc: false,
  });
  return result ? result.code : '';
}

/**
 * Transforms and executes JavaScript code containing object definitions with duplicate keys.
 *
 * @param {string} sourceCode - JavaScript snippet that assigns results to variable `output`.
 * @param {object} [options] - Plugin options.
 * @returns {*} The evaluated output value.
 */
function evaluateDuplicateKeys(sourceCode, options = {}) {
  const transformed = transformDuplicateKeysCode(sourceCode, options);
  let output;
  eval(transformed);
  return output;
}

module.exports = {
  transformDuplicateKeys,
  transformDuplicateKeysCode,
  evaluateDuplicateKeys,
};
test/contract.js
'use strict';

const assert = require('node:assert/strict');
const transformDuplicateKeys = require('@babel/plugin-transform-duplicate-keys');
const {
  transformDuplicateKeysCode,
  evaluateDuplicateKeys,
} = require('../src/index.js');

// Contract 1: assert @babel/plugin-transform-duplicate-keys exports a Babel plugin factory function
{
  assert.strictEqual(typeof transformDuplicateKeys, 'object', 'Plugin module should be an object');
  assert.strictEqual(typeof transformDuplicateKeys.default, 'function', 'Plugin default export should be a function');
}

// Contract 2: assert duplicate identifier keys in object literals are transformed to computed string property keys
{
  const code = 'output = { a: 10, a: 20 };';
  const transformed = transformDuplicateKeysCode(code);
  assert.ok(transformed.includes('["a"]'), 'Second duplicate key "a" should be transformed to computed property ["a"]');
  const result = evaluateDuplicateKeys(code);
  assert.deepStrictEqual(result, { a: 20 }, 'Evaluated object should retain the value of the overridden property');
}

// Contract 3: assert duplicate string literal keys and matching identifier keys are transformed to computed keys
{
  const code = 'output = { "key-name": "first", "key-name": "second", title: "old", "title": "new" };';
  const transformed = transformDuplicateKeysCode(code);
  assert.ok(transformed.includes('["key-name"]'), 'Duplicate string key should be transformed to computed property');
  assert.ok(transformed.includes('["title"]'), 'Duplicate identifier-string key collision should be transformed to computed property');
  const result = evaluateDuplicateKeys(code);
  assert.deepStrictEqual(result, { 'key-name': 'second', title: 'new' });
}

// Contract 4: assert duplicate numeric literal keys and matching string keys are normalized and transformed to computed keys
{
  const code = 'output = { 42: "num", "42": "str", 100: "first", 100: "second" };';
  const transformed = transformDuplicateKeysCode(code);
  assert.ok(transformed.includes('["42"]'), 'Duplicate numeric/string key should be transformed to computed property');
  assert.ok(transformed.includes('["100"]'), 'Duplicate numeric literal should be transformed to computed property');
  const result = evaluateDuplicateKeys(code);
  assert.deepStrictEqual(result, { 42: 'str', 100: 'second' });
}

// Contract 5: assert getter and setter properties with duplicate keys are transformed into computed getters or properties
{
  const getterCode = `
    output = {
      get value() { return 100; },
      value: 200
    };
  `;
  const transformedGetter = transformDuplicateKeysCode(getterCode);
  assert.ok(transformedGetter.includes('["value"]'), 'Value property after getter should be transformed to computed key');
  const resultGetter = evaluateDuplicateKeys(getterCode);
  assert.strictEqual(resultGetter.value, 200);

  const twoGettersCode = `
    output = {
      get item() { return "v1"; },
      get item() { return "v2"; }
    };
  `;
  const transformedTwoGetters = transformDuplicateKeysCode(twoGettersCode);
  assert.ok(transformedTwoGetters.includes('get ["item"]'), 'Subsequent getter should be transformed to computed getter');
  const resultTwoGetters = evaluateDuplicateKeys(twoGettersCode);
  assert.strictEqual(resultTwoGetters.item, 'v2');
}

// Contract 6: assert multiple successive duplicate keys in object literals and nested objects are all transformed into computed keys
{
  const code = `
    output = {
      val: 1,
      val: 2,
      val: 3,
      nested: {
        x: 'a',
        x: 'b'
      }
    };
  `;
  const transformed = transformDuplicateKeysCode(code);
  const occurrences = transformed.split('["val"]').length - 1;
  assert.strictEqual(occurrences, 2, 'Should transform each subsequent duplicate of val into computed properties');
  assert.ok(transformed.includes('["x"]'), 'Nested object duplicate keys should be transformed');
  const result = evaluateDuplicateKeys(code);
  assert.deepStrictEqual(result, {
    val: 3,
    nested: { x: 'b' },
  });
}

// Contract 7: assert non-duplicate object properties remain untransformed standard properties
{
  const code = 'output = { alpha: 1, beta: 2, gamma: 3 };';
  const transformed = transformDuplicateKeysCode(code);
  assert.ok(!transformed.includes('['), 'Non-duplicate properties should not have computed keys');
  const result = evaluateDuplicateKeys(code);
  assert.deepStrictEqual(result, { alpha: 1, beta: 2, gamma: 3 });
}

console.log('All @babel/plugin-transform-duplicate-keys contract assertions passed.');

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