@humanwhocodes/module-importer 1.0.1: ModuleImporter

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 @humanwhocodes/module-importer.ModuleImporter in pkg:npm/%40humanwhocodes/module-importer@1.0.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40humanwhocodes/module-importer@1.0.1
Demonstrate these symbols/APIs:
  - @humanwhocodes/module-importer.ModuleImporter
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - runtime: node@22.23.2

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.

{"case":{"caseId":"case:sha256:8635c87d4b27f6a7c4988cff803f02bc34e580f72ef9439f28221c2be634c920","constraints":{"executionContext":"node"},"contract":["ModuleImporter constructs with base working directory","ModuleImporter.resolve returns absolute path for CommonJS file","ModuleImporter.resolve returns absolute path for ESM file","ModuleImporter.import loads CommonJS module asynchronously","ModuleImporter.import loads ESM module asynchronously"],"goal":"verify @humanwhocodes/module-importer.ModuleImporter in pkg:npm/%40humanwhocodes/module-importer@1.0.1","kind":"HOW","packages":["pkg:npm/%40humanwhocodes/module-importer@1.0.1"],"schemaVersion":1,"symbols":["@humanwhocodes/module-importer.ModuleImporter"]},"contractCommand":["node","test/contract.js"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/%40humanwhocodes/module-importer@1.0.1"],"schemaVersion":1,"subject":"pkg:npm/%40humanwhocodes/module-importer@1.0.1","symbols":["@humanwhocodes/module-importer.ModuleImporter"],"verifierAdapter":"node-typescript@1"}

module.exports = {
  type: "commonjs",
  add: (a, b) => a + b,
  message: "cjs-success"
};

export const type = "esm";
export const multiply = (a, b) => a * b;
export const message = "esm-success";

const { ModuleImporter } = require("@humanwhocodes/module-importer");

function createModuleImporter(baseDir) {
  return new ModuleImporter(baseDir);
}

module.exports = {
  ModuleImporter,
  createModuleImporter
};

{
  "name": "module-importer-sample",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "module-importer-sample",
      "version": "1.0.0",
      "dependencies": {
        "@humanwhocodes/module-importer": "1.0.1"
      }
    },
    "node_modules/@humanwhocodes/module-importer": {
      "version": "1.0.1",
      "resolved": "https://registry.npmjs.org/@humanwhocodes/module-importer/-/module-importer-1.0.1.tgz",
      "integrity": "sha512-bxveV4V8v5Yb4ncFTT3rPSgZBOpCkjfK0y4oVVVJwIuDVBRMDXrPyXRL988i5ap9m9bnyEEjWfm5WkBmtffLfA==",
      "license": "Apache-2.0",
      "engines": {
        "node": ">=12.22"
      },
      "funding": {
        "type": "github",
        "url": "https://github.com/sponsors/nzakas"
      }
    }
  }
}

{
  "name": "module-importer-sample",
  "version": "1.0.0",
  "private": true,
  "description": "Clean-room verification sample for @humanwhocodes/module-importer",
  "main": "index.js",
  "scripts": {
    "test": "node test/contract.js"
  },
  "dependencies": {
    "@humanwhocodes/module-importer": "1.0.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify @humanwhocodes/module-importer.ModuleImporter in pkg:npm/%40humanwhocodes/module-importer@1.0.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40humanwhocodes/module-importer@1.0.1"
  ],
  "symbols": [
    "@humanwhocodes/module-importer.ModuleImporter"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "runtime": "node@22.23.2"
  }
}

const assert = require("assert");
const path = require("path");
const { ModuleImporter } = require("@humanwhocodes/module-importer");

async function runContractTests() {
  const fixturesDir = path.resolve(__dirname, "../fixtures");
  const importer = new ModuleImporter(fixturesDir);

  // Contract 1: ModuleImporter constructs with base working directory
  assert.ok(importer instanceof ModuleImporter, "importer must be instance of ModuleImporter");
  assert.strictEqual(typeof importer.cwd, "string", "importer.cwd must be a string");
  assert.ok(importer.cwd.endsWith("/"), "importer.cwd must end with a trailing slash");

  // Contract 2: ModuleImporter.resolve returns absolute path for CommonJS file
  const cjsPath = importer.resolve("./sample-cjs.cjs");
  assert.strictEqual(typeof cjsPath, "string", "resolve should return string path");
  assert.ok(cjsPath.endsWith("sample-cjs.cjs"), "resolve path should end with sample-cjs.cjs");

  // Contract 3: ModuleImporter.resolve returns absolute path for ESM file
  const esmPath = importer.resolve("./sample-esm.mjs");
  assert.strictEqual(typeof esmPath, "string", "resolve should return string path");
  assert.ok(esmPath.endsWith("sample-esm.mjs"), "resolve path should end with sample-esm.mjs");

  // Contract 4: ModuleImporter.import loads CommonJS module asynchronously
  const cjsModule = await importer.import("./sample-cjs.cjs");
  assert.ok(cjsModule, "imported cjs module must be defined");
  assert.ok(cjsModule.default, "cjs module default export must be present");
  assert.strictEqual(cjsModule.default.type, "commonjs", "cjs module type must match");
  assert.strictEqual(cjsModule.default.add(5, 7), 12, "cjs add function must compute correctly");
  assert.strictEqual(cjsModule.default.message, "cjs-success", "cjs message must match");

  // Contract 5: ModuleImporter.import loads ESM module asynchronously
  const esmModule = await importer.import("./sample-esm.mjs");
  assert.ok(esmModule, "imported esm module must be defined");
  assert.strictEqual(esmModule.type, "esm", "esm module type must match");
  assert.strictEqual(esmModule.multiply(6, 7), 42, "esm multiply function must compute correctly");
  assert.strictEqual(esmModule.message, "esm-success", "esm message must match");

  console.log("Contract verified successfully.");
}

runContractTests().catch((error) => {
  console.error("Contract test failed:", error);
  process.exit(1);
});