CodeSampleX

Sample

@babel/core 7.29.6: buildExternalHelpers

Verified sample for npm @babel/core 7.29.6: buildExternalHelpers. The contract ran on node 22 · linux debian/x64 · docker and passed.

sha256:375672659ed8567ff7a1ce254f0bf35538a0c94a7a1f5c56d28313d61be443e9

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…		 2026-09-03

Case

HOW
Goal
verify pkg:npm/%40babel/core@7.29.6
Packages
Symbols
  • buildExternalHelpers
Created
2026-09-03T10:09:38Z

Contract

  1. babel.buildExternalHelpers is exported as a function by @babel/core and returns a string of helper definitions
  2. buildExternalHelpers defaults to global outputType wrapping helpers in an IIFE assigning to global.babelHelpers
  3. buildExternalHelpers produces UMD formatted wrapper when outputType is set to umd
  4. buildExternalHelpers produces standalone var declarations when outputType is set to var
  5. buildExternalHelpers restricts generated code to specified helpers when whitelist array is provided
  6. buildExternalHelpers outputs only the container wrapper without helper implementations when whitelist is empty array
  7. buildExternalHelpers throws an Error with Unsupported output type message when given an invalid outputType
  8. buildExternalHelpers requires explicit dependency inclusion in whitelist for composite helpers such as inherits requiring setPrototypeOf

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/core@7.29.6
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40babel/core@7.29.6
Demonstrate these symbols/APIs:
  - buildExternalHelpers

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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  "name": "sample-babel-core-build-external-helpers",
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package.json
{
  "name": "sample-babel-core-build-external-helpers",
  "version": "1.0.0",
  "description": "verify @babel/core.buildExternalHelpers in pkg:npm/%40babel/core@7.29.6",
  "type": "module",
  "main": "src/index.mjs",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "@babel/core": "7.29.6"
  },
  "license": "MIT-0"
}
spec.json
{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/%40babel/core@7.29.6",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40babel/core@7.29.6"
  ],
  "symbols": [
    "buildExternalHelpers"
  ]
}
src/index.mjs
import * as babel from "@babel/core";

/**
 * Builds external helper code from @babel/core.
 *
 * @param {string[]|null|undefined} [whitelist] - List of helper names to include.
 * @param {"global"|"umd"|"var"} [outputType="global"] - Output format type.
 * @returns {string} The generated helper code.
 */
export function buildHelpers(whitelist, outputType) {
  return babel.buildExternalHelpers(whitelist, outputType);
}

/**
 * Generates external helpers in var format for a given whitelist.
 *
 * @param {string[]} [whitelist] - List of helper names to include.
 * @returns {string} The generated var-format helper code.
 */
export function buildVarHelpers(whitelist) {
  return babel.buildExternalHelpers(whitelist, "var");
}

/**
 * Evaluates var-format helper code in an isolated scope and returns the babelHelpers object.
 *
 * @param {string[]} [whitelist] - List of helper names to include.
 * @returns {Record<string, Function>} The instantiated babelHelpers object.
 */
export function evaluateVarHelpers(whitelist) {
  const code = buildVarHelpers(whitelist);
  const factory = new Function(code + "; return babelHelpers;");
  return factory();
}

export { babel };
test/contract.mjs
import assert from "node:assert/strict";
import * as babel from "@babel/core";
import {
  buildHelpers,
  buildVarHelpers,
  evaluateVarHelpers,
} from "../src/index.mjs";

function runContracts() {
  // Contract 1: babel.buildExternalHelpers is exported as a function by @babel/core and returns a string of helper definitions
  {
    assert.strictEqual(
      typeof babel.buildExternalHelpers,
      "function",
      "babel.buildExternalHelpers must be exported as a function"
    );

    const result = buildHelpers();
    assert.strictEqual(
      typeof result,
      "string",
      "buildExternalHelpers must return a string"
    );
    assert.ok(
      result.length > 0,
      "generated helpers string must not be empty"
    );
  }

  // Contract 2: buildExternalHelpers defaults to global outputType wrapping helpers in an IIFE assigning to global.babelHelpers
  {
    const result = buildHelpers();
    assert.ok(
      result.includes("global.babelHelpers = {}"),
      "default output must assign to global.babelHelpers"
    );
    assert.ok(
      result.includes('typeof global === "undefined" ? self : global'),
      "default output must detect global or self in IIFE invocation"
    );
  }

  // Contract 3: buildExternalHelpers produces UMD formatted wrapper when outputType is set to umd
  {
    const result = buildHelpers(undefined, "umd");
    assert.strictEqual(
      typeof result,
      "string",
      "umd output must be a string"
    );
    assert.ok(
      result.includes('typeof define === "function" && define.amd'),
      "umd output must check for define.amd"
    );
    assert.ok(
      result.includes("factory(root.babelHelpers = {})"),
      "umd output must invoke factory with root.babelHelpers"
    );
  }

  // Contract 4: buildExternalHelpers produces standalone var declarations when outputType is set to var
  {
    const result = buildHelpers(undefined, "var");
    assert.strictEqual(
      typeof result,
      "string",
      "var output must be a string"
    );
    assert.ok(
      result.startsWith("var babelHelpers = {};"),
      "var output must declare babelHelpers variable at top"
    );
    assert.ok(
      result.trimEnd().endsWith("babelHelpers;"),
      "var output must end with babelHelpers reference expression"
    );
  }

  // Contract 5: buildExternalHelpers restricts generated code to specified helpers when whitelist array is provided
  {
    const result = buildHelpers(["classCallCheck"], "var");
    assert.ok(
      result.includes("classCallCheck"),
      "whitelisted helper classCallCheck must be present"
    );
    assert.ok(
      !result.includes("_inherits"),
      "unselected helper inherits must not be included"
    );
  }

  // Contract 6: buildExternalHelpers outputs only the container wrapper without helper implementations when whitelist is empty array
  {
    const result = buildHelpers([], "var");
    assert.strictEqual(
      result.trim(),
      "var babelHelpers = {};\nbabelHelpers;",
      "empty whitelist must produce only empty container shell"
    );
  }

  // Contract 7: buildExternalHelpers throws an Error with Unsupported output type message when given an invalid outputType
  {
    assert.throws(
      () => {
        buildHelpers(undefined, "unsupported_format");
      },
      (err) => {
        return err instanceof Error && /Unsupported output type/i.test(err.message);
      },
      "must throw error matching Unsupported output type for invalid outputType"
    );
  }

  // Contract 8: buildExternalHelpers requires explicit dependency inclusion in whitelist for composite helpers such as inherits requiring setPrototypeOf
  {
    const helpersOnlyInherits = evaluateVarHelpers(["inherits"]);
    assert.strictEqual(
      typeof helpersOnlyInherits.inherits,
      "function",
      "inherits must be defined when requested"
    );
    assert.strictEqual(
      typeof helpersOnlyInherits.setPrototypeOf,
      "undefined",
      "setPrototypeOf must not be included automatically when not in whitelist"
    );

    const fullHelpers = evaluateVarHelpers(["inherits", "setPrototypeOf"]);
    assert.strictEqual(
      typeof fullHelpers.inherits,
      "function",
      "inherits must be defined"
    );
    assert.strictEqual(
      typeof fullHelpers.setPrototypeOf,
      "function",
      "setPrototypeOf must be defined"
    );

    function SuperType() {}
    SuperType.prototype.identify = function () {
      return "base";
    };

    function SubType() {}
    fullHelpers.inherits(SubType, SuperType);

    const instance = new SubType();
    assert.ok(
      instance instanceof SuperType,
      "instance of SubType must be an instance of SuperType via inherits"
    );
    assert.strictEqual(
      instance.identify(),
      "base",
      "inherited prototype method must return expected value"
    );
  }

  console.log("All contract assertions passed successfully.");
}

runContracts();

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