@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 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
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - 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:sha256:35d0e130703cfd4f02a743fa3e0154bde0af5eb261067007f0d84fb9c15b3a47","constraints":{"executionContext":"node"},"contract":["ModuleImporter constructs with default or custom working directory","ModuleImporter.resolve resolves relative CommonJS module path to absolute path","ModuleImporter.resolve resolves relative ESM module path to absolute path","ModuleImporter.resolve throws error when module cannot be located","ModuleImporter.import dynamically imports CommonJS module","ModuleImporter.import dynamically imports ESM module"],"goal":"verify 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","packageManagerVersion":"10.9.8","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 = {
  kind: "commonjs",
  compute: (x, y) => x + y
};

export const kind = "esm";
export const compute = (x, y) => x * y;

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

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

module.exports = {
  ModuleImporter,
  createImporter
};

{
  "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 pkg:npm/%40humanwhocodes/module-importer@1.0.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40humanwhocodes/module-importer@1.0.1"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

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

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

  // 1. ModuleImporter constructs with default or custom working directory
  assert.ok(importer instanceof ModuleImporter, "importer must be instance of ModuleImporter");
  assert.strictEqual(typeof importer.cwd, "string", "importer.cwd must be string");
  assert.ok(importer.cwd.endsWith("/"), "importer.cwd must end with slash");

  const defaultImporter = new ModuleImporter();
  assert.ok(defaultImporter instanceof ModuleImporter, "default importer must be instance of ModuleImporter");
  assert.ok(defaultImporter.cwd.endsWith("/"), "default importer cwd must end with slash");

  // 2. ModuleImporter.resolve resolves relative CommonJS module path to absolute path
  const cjsResolved = importer.resolve("./sample-cjs.cjs");
  assert.strictEqual(typeof cjsResolved, "string", "resolve should return string path");
  assert.ok(cjsResolved.endsWith("sample-cjs.cjs"), "resolved path should end with sample-cjs.cjs");

  // 3. ModuleImporter.resolve resolves relative ESM module path to absolute path
  const esmResolved = importer.resolve("./sample-esm.mjs");
  assert.strictEqual(typeof esmResolved, "string", "resolve should return string path");
  assert.ok(esmResolved.endsWith("sample-esm.mjs"), "resolved path should end with sample-esm.mjs");

  // 4. ModuleImporter.resolve throws error when module cannot be located
  assert.throws(
    () => importer.resolve("./non-existent-module.js"),
    /MODULE_NOT_FOUND|Cannot find module/
  );

  // 5. ModuleImporter.import dynamically imports CommonJS module
  const cjsModule = await importer.import("./sample-cjs.cjs");
  assert.ok(cjsModule, "imported cjs module must be defined");
  assert.strictEqual(cjsModule.default.kind, "commonjs", "cjs kind must match");
  assert.strictEqual(cjsModule.default.compute(10, 20), 30, "cjs compute must match");

  // 6. ModuleImporter.import dynamically imports ESM module
  const esmModule = await importer.import("./sample-esm.mjs");
  assert.ok(esmModule, "imported esm module must be defined");
  assert.strictEqual(esmModule.kind, "esm", "esm kind must match");
  assert.strictEqual(esmModule.compute(10, 20), 200, "esm compute must match");

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

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