bare-os 3.9.3: cpuUsage

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 cpuUsage in pkg:npm/bare-os@3.9.3
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/bare-os@3.9.3
Demonstrate these symbols/APIs:
  - cpuUsage

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:eade65e92af16f45bd5f43c3f37b5c20aea68bb715f36870bc0347dd92537621","contract":["package manifest specifies bare-os name, version 3.9.3, addon configuration, and Bare engine requirement","declares CpuUsage interface and cpuUsage function accepting optional previous CpuUsage in index.d.ts","native binding implements bare_os_cpu_usage querying process CPU times with uv_getrusage","cpuUsage() returns current process user and system CPU times in microseconds","cpuUsage(previous) calculates diff between current and previous user and system CPU times"],"goal":"verify cpuUsage in pkg:npm/bare-os@3.9.3","kind":"HOW","packages":["pkg:npm/bare-os@3.9.3"],"schemaVersion":1,"symbols":["cpuUsage"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/bare-os@3.9.3"],"schemaVersion":1,"subject":"pkg:npm/bare-os@3.9.3","symbols":["cpuUsage"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-bare-os-cpu-usage",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-bare-os-cpu-usage",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "bare-os": "3.9.3"
      }
    },
    "node_modules/bare-os": {
      "version": "3.9.3",
      "resolved": "https://registry.npmjs.org/bare-os/-/bare-os-3.9.3.tgz",
      "integrity": "sha512-fF4Q7QsyKVF5Rj0qvI8BgUNjqzC2JvQlpTaPLjVJVxYVUX5Zr9un+y3w1HmA4nNKdFmRBT8z/WmrjvXzXVerKQ==",
      "license": "Apache-2.0",
      "engines": {
        "bare": ">=1.14.0"
      }
    }
  }
}

{
  "name": "sample-bare-os-cpu-usage",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "license": "MIT-0",
  "dependencies": {
    "bare-os": "3.9.3"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify cpuUsage in pkg:npm/bare-os@3.9.3",
  "kind": "HOW",
  "packages": [
    "pkg:npm/bare-os@3.9.3"
  ],
  "symbols": [
    "cpuUsage"
  ]
}

import fs from 'node:fs';
import path from 'node:path';
import { createRequire } from 'node:module';

const require = createRequire(import.meta.url);

/**
 * Validates that an object conforms to the bare-os CpuUsage interface.
 *
 * @param {unknown} usage - The CPU usage object to validate.
 * @returns {boolean} True if usage contains finite non-negative numeric user and system properties.
 * @throws {TypeError} If usage is not an object or user/system are not finite numbers.
 */
export function validateCpuUsage(usage) {
  if (usage === null || typeof usage !== 'object') {
    throw new TypeError(`CpuUsage must be an object. Received ${typeof usage}`);
  }

  const { user, system } = usage;
  if (typeof user !== 'number' || !Number.isFinite(user) || user < 0) {
    throw new TypeError(`Field "user" must be a non-negative finite number. Received ${typeof user} (${user})`);
  }
  if (typeof system !== 'number' || !Number.isFinite(system) || system < 0) {
    throw new TypeError(`Field "system" must be a non-negative finite number. Received ${typeof system} (${system})`);
  }

  return true;
}

/**
 * Calculates CPU time delta between two CpuUsage snapshots.
 *
 * @param {import('bare-os').CpuUsage} previous - Previous CPU usage snapshot.
 * @param {import('bare-os').CpuUsage} current - Current CPU usage snapshot.
 * @returns {{ user: number, system: number, total: number }}
 */
export function calculateCpuUsageDelta(previous, current) {
  validateCpuUsage(previous);
  validateCpuUsage(current);

  const userDelta = Math.max(0, current.user - previous.user);
  const systemDelta = Math.max(0, current.system - previous.system);

  return {
    user: userDelta,
    system: systemDelta,
    total: userDelta + systemDelta,
  };
}

/**
 * Formats CPU usage in microseconds to milliseconds and seconds for human-readable reporting.
 *
 * @param {import('bare-os').CpuUsage} usage - CPU usage in microseconds.
 * @returns {{ userMs: number, systemMs: number, userSec: number, systemSec: number }}
 */
export function formatCpuUsage(usage) {
  validateCpuUsage(usage);

  return {
    userMs: usage.user / 1000,
    systemMs: usage.system / 1000,
    userSec: usage.user / 1e6,
    systemSec: usage.system / 1e6,
  };
}

/**
 * Reads bare-os package manifest.
 *
 * @returns {object} The parsed package.json manifest.
 */
export function getBareOsPackage() {
  const pkgPath = require.resolve('bare-os/package');
  return JSON.parse(fs.readFileSync(pkgPath, 'utf8'));
}

/**
 * Reads bare-os package source files and declarations.
 *
 * @returns {{ pkgDir: string, indexJs: string, indexDts: string, bindingC: string }}
 */
export function getBareOsSource() {
  const pkgDir = path.dirname(require.resolve('bare-os/package'));
  const indexJs = fs.readFileSync(path.join(pkgDir, 'index.js'), 'utf8');
  const indexDts = fs.readFileSync(path.join(pkgDir, 'index.d.ts'), 'utf8');
  const bindingC = fs.readFileSync(path.join(pkgDir, 'binding.c'), 'utf8');
  return { pkgDir, indexJs, indexDts, bindingC };
}

/**
 * Inspects bare-os cpuUsage API contract across JS wrapper, TS declarations, and C bindings.
 *
 * @returns {{ hasJsExport: boolean, hasJsDeltaCalculation: boolean, hasTsDeclaration: boolean, hasTsInterface: boolean, hasBindingRegistration: boolean, hasBindingFunction: boolean }}
 */
export function inspectCpuUsageApiContract() {
  const { indexJs, indexDts, bindingC } = getBareOsSource();

  const hasJsExport = indexJs.includes('exports.cpuUsage = function cpuUsage(previous)');
  const hasJsDeltaCalculation =
    indexJs.includes('user: current.user - previous.user') &&
    indexJs.includes('system: current.system - previous.system');

  const hasTsDeclaration = indexDts.includes('export function cpuUsage(previous?: CpuUsage): CpuUsage');
  const hasTsInterface = indexDts.includes('export interface CpuUsage {\n  user: number\n  system: number\n}');

  const hasBindingRegistration = bindingC.includes('V("cpuUsage", bare_os_cpu_usage)');
  const hasBindingFunction =
    bindingC.includes('bare_os_cpu_usage(js_env_t *env, js_callback_info_t *info)') &&
    bindingC.includes('uv_getrusage(&usage)');

  return {
    hasJsExport,
    hasJsDeltaCalculation,
    hasTsDeclaration,
    hasTsInterface,
    hasBindingRegistration,
    hasBindingFunction,
  };
}

import assert from 'node:assert/strict';
import { createRequire } from 'node:module';
import path from 'node:path';
import {
  validateCpuUsage,
  calculateCpuUsageDelta,
  formatCpuUsage,
  getBareOsPackage,
  getBareOsSource,
  inspectCpuUsageApiContract,
} from '../src/index.mjs';

const require = createRequire(import.meta.url);

// 1. Verify bare-os package manifest and metadata
const pkg = getBareOsPackage();
assert.equal(pkg.name, 'bare-os', 'Package name must be bare-os');
assert.equal(pkg.version, '3.9.3', 'Package version must be 3.9.3');
assert.equal(pkg.license, 'Apache-2.0', 'Package license must be Apache-2.0');
assert.equal(pkg.addon, true, 'Package must be marked as addon');
assert.equal(pkg.engines?.bare, '>=1.14.0', 'Package must specify Bare engine requirement >=1.14.0');
assert.ok(pkg.exports, 'Package must define exports map');
assert.equal(pkg.exports['.'].types, './index.d.ts', 'Root export must specify index.d.ts types');
assert.equal(pkg.exports['.'].default, './index.js', 'Root export must specify index.js default');

// 2. Verify TypeScript type definitions for cpuUsage
const { pkgDir, indexJs, indexDts, bindingC } = getBareOsSource();
assert.ok(
  indexDts.includes('export interface CpuUsage {\n  user: number\n  system: number\n}'),
  'index.d.ts must declare CpuUsage interface with user and system properties'
);
assert.ok(
  indexDts.includes('export function cpuUsage(previous?: CpuUsage): CpuUsage'),
  'index.d.ts must declare cpuUsage function accepting optional previous CpuUsage'
);

// 3. Verify JavaScript export and implementation in index.js
assert.ok(
  indexJs.includes('exports.cpuUsage = function cpuUsage(previous)'),
  'index.js must export cpuUsage function'
);
assert.ok(
  indexJs.includes('const current = binding.cpuUsage()'),
  'cpuUsage must call binding.cpuUsage()'
);
assert.ok(
  indexJs.includes('user: current.user - previous.user'),
  'cpuUsage must compute user CPU time difference when previous is provided'
);
assert.ok(
  indexJs.includes('system: current.system - previous.system'),
  'cpuUsage must compute system CPU time difference when previous is provided'
);

// 4. Verify C native binding implementation for cpuUsage
assert.ok(
  bindingC.includes('bare_os_cpu_usage(js_env_t *env, js_callback_info_t *info)'),
  'binding.c must implement bare_os_cpu_usage'
);
assert.ok(
  bindingC.includes('uv_getrusage(&usage)'),
  'binding.c must query process resource usage via uv_getrusage'
);
assert.ok(
  bindingC.includes('V("cpuUsage", bare_os_cpu_usage)'),
  'binding.c must register bare_os_cpu_usage under cpuUsage'
);

// 5. Verify contract inspection helper
const inspection = inspectCpuUsageApiContract();
assert.equal(inspection.hasJsExport, true, 'inspectCpuUsageApiContract reports JS export present');
assert.equal(inspection.hasJsDeltaCalculation, true, 'inspectCpuUsageApiContract reports JS delta calculation present');
assert.equal(inspection.hasTsDeclaration, true, 'inspectCpuUsageApiContract reports TS declaration present');
assert.equal(inspection.hasTsInterface, true, 'inspectCpuUsageApiContract reports TS interface present');
assert.equal(inspection.hasBindingRegistration, true, 'inspectCpuUsageApiContract reports binding registration present');
assert.equal(inspection.hasBindingFunction, true, 'inspectCpuUsageApiContract reports binding function present');

// 6. Verify runtime behavior of cpuUsage() and cpuUsage(previous)
const bindingPath = path.join(pkgDir, 'binding.js');
let simulatedProcessUsage = { user: 250000, system: 80000 };

require.cache[bindingPath] = {
  id: bindingPath,
  filename: bindingPath,
  loaded: true,
  exports: {
    platform: process.platform,
    arch: process.arch,
    cpuUsage: () => ({ ...simulatedProcessUsage }),
  },
};

const bareOs = require('bare-os');
assert.equal(typeof bareOs.cpuUsage, 'function', 'bare-os must export cpuUsage function');

// Test 6a: Calling cpuUsage() without previous usage returns current process CPU times
const usage1 = bareOs.cpuUsage();
assert.equal(typeof usage1, 'object', 'cpuUsage must return an object');
assert.equal(usage1.user, 250000, 'usage.user must match simulated user time in microseconds');
assert.equal(usage1.system, 80000, 'usage.system must match simulated system time in microseconds');
assert.equal(validateCpuUsage(usage1), true, 'usage1 must pass CpuUsage validation');

// Test 6b: Calling cpuUsage(previous) computes delta
simulatedProcessUsage = { user: 320000, system: 110000 };
const usageDiff = bareOs.cpuUsage(usage1);
assert.equal(usageDiff.user, 70000, 'diff.user must be 320000 - 250000 = 70000');
assert.equal(usageDiff.system, 30000, 'diff.system must be 110000 - 80000 = 30000');
assert.equal(validateCpuUsage(usageDiff), true, 'usageDiff must pass CpuUsage validation');

// Test 6c: Calling cpuUsage with zero previous
const usageDiffZero = bareOs.cpuUsage({ user: 0, system: 0 });
assert.equal(usageDiffZero.user, 320000, 'diff against zero must equal current user time');
assert.equal(usageDiffZero.system, 110000, 'diff against zero must equal current system time');

// 7. Verify helper functions: delta calculation and formatting
const helperDelta = calculateCpuUsageDelta(usage1, simulatedProcessUsage);
assert.equal(helperDelta.user, 70000, 'helper user delta matches');
assert.equal(helperDelta.system, 30000, 'helper system delta matches');
assert.equal(helperDelta.total, 100000, 'helper total delta matches');

const formatted = formatCpuUsage(usage1);
assert.equal(formatted.userMs, 250, 'user time in ms must be 250');
assert.equal(formatted.systemMs, 80, 'system time in ms must be 80');
assert.equal(formatted.userSec, 0.25, 'user time in seconds must be 0.25');
assert.equal(formatted.systemSec, 0.08, 'system time in seconds must be 0.08');

// Verify validation errors on invalid inputs
assert.throws(() => validateCpuUsage(null), TypeError);
assert.throws(() => validateCpuUsage({ user: 'invalid', system: 10 }), TypeError);
assert.throws(() => validateCpuUsage({ user: 10, system: -5 }), TypeError);
assert.throws(() => validateCpuUsage({ user: 10 }), TypeError);

console.log('Contract verification finished successfully for bare-os cpuUsage.');