esbuild 0.28.2

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/esbuild@0.28.2
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/esbuild@0.28.2

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:sha256:3c9c0108451eee38953dbcb0b952022c0329496c5825b1b312063cfda2b69a88","contract":["assert esbuild exports expected version 0.28.2","assert esbuild.buildSync bundles TypeScript source code into ESM in memory","assert esbuild.transformSync transpiles JSX syntax to JavaScript with minification","assert esbuild.formatMessagesSync formats diagnostic error messages with file location and source line context","assert esbuild.analyzeMetafileSync computes formatted bundle breakdown from build metafile"],"goal":"verify pkg:npm/esbuild@0.28.2","kind":"HOW","packages":["pkg:npm/esbuild@0.28.2"],"schemaVersion":1},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/esbuild@0.28.2"],"schemaVersion":1,"subject":"pkg:npm/esbuild@0.28.2","verifierAdapter":"node-typescript@1"}

{
  "name": "sample-esbuild",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-esbuild",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "esbuild": "0.28.2"
      }
    },
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      "cpu": [
        "ppc64"
      ],
      "license": "MIT",
      "optional": true,
      "os": [
        "aix"
      ],
      "engines": {
        "node": ">=18"
      }
    },
    "node_modules/@esbuild/android-arm": {
      "version": "0.28.2",
      "resolved": "https://registry.npmjs.org/@esbuild/android-arm/-/android-arm-0.28.2.tgz",
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      "cpu": [
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      "license": "MIT",
      "optional": true,
      "os": [
        "android"
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      "engines": {
        "node": ">=18"
      }
    },
    "node_modules/@esbuild/android-arm64": {
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      "resolved": "https://registry.npmjs.org/@esbuild/android-arm64/-/android-arm64-0.28.2.tgz",
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      "cpu": [
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      "license": "MIT",
      "optional": true,
      "os": [
        "android"
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      "engines": {
        "node": ">=18"
      }
    },
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      "version": "0.28.2",
      "resolved": "https://registry.npmjs.org/@esbuild/android-x64/-/android-x64-0.28.2.tgz",
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      "engines": {
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      "optional": true,
      "os": [
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      "engines": {
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      "optional": true,
      "os": [
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      "engines": {
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      "engines": {
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      "os": [
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      "engines": {
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    "node_modules/@esbuild/linux-mips64el": {
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      "optional": true,
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      "engines": {
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      "optional": true,
      "os": [
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      "engines": {
        "node": ">=18"
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      "optional": true,
      "os": [
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      "engines": {
        "node": ">=18"
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    "node_modules/@esbuild/openharmony-arm64": {
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      "optional": true,
      "os": [
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      "engines": {
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      "optional": true,
      "os": [
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      "engines": {
        "node": ">=18"
      }
    },
    "node_modules/@esbuild/win32-ia32": {
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      "engines": {
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    "node_modules/@esbuild/win32-x64": {
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      "optional": true,
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      "hasInstallScript": true,
      "license": "MIT",
      "bin": {
        "esbuild": "bin/esbuild"
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      "engines": {
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      "optionalDependencies": {
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        "@esbuild/darwin-arm64": "0.28.2",
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        "@esbuild/freebsd-arm64": "0.28.2",
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        "@esbuild/linux-arm": "0.28.2",
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        "@esbuild/linux-riscv64": "0.28.2",
        "@esbuild/linux-s390x": "0.28.2",
        "@esbuild/linux-x64": "0.28.2",
        "@esbuild/netbsd-arm64": "0.28.2",
        "@esbuild/netbsd-x64": "0.28.2",
        "@esbuild/openbsd-arm64": "0.28.2",
        "@esbuild/openbsd-x64": "0.28.2",
        "@esbuild/openharmony-arm64": "0.28.2",
        "@esbuild/sunos-x64": "0.28.2",
        "@esbuild/win32-arm64": "0.28.2",
        "@esbuild/win32-ia32": "0.28.2",
        "@esbuild/win32-x64": "0.28.2"
      }
    }
  }
}

{
  "name": "sample-esbuild",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "license": "MIT-0",
  "main": "src/index.mjs",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "esbuild": "0.28.2"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/esbuild@0.28.2",
  "kind": "HOW",
  "packages": [
    "pkg:npm/esbuild@0.28.2"
  ]
}

import * as esbuild from 'esbuild';

/**
 * Bundles TypeScript or JavaScript source code in memory.
 * @param {string} contents - Source code contents.
 * @param {'ts' | 'js' | 'jsx' | 'tsx'} loader - Loader type.
 * @returns {import('esbuild').BuildResult} Build result object.
 */
export function bundleInMemory(contents, loader = 'ts') {
  return esbuild.buildSync({
    stdin: {
      contents,
      loader,
      resolveDir: process.cwd(),
    },
    format: 'esm',
    write: false,
    bundle: true,
  });
}

/**
 * Transpiles and minifies source code.
 * @param {string} contents - Source code contents.
 * @param {import('esbuild').TransformOptions} options - Transform options.
 * @returns {import('esbuild').TransformResult} Transform result object.
 */
export function transformSource(contents, options = {}) {
  return esbuild.transformSync(contents, options);
}

/**
 * Formats diagnostic messages.
 * @param {import('esbuild').PartialMessage[]} messages - Diagnostic messages.
 * @param {import('esbuild').FormatMessagesOptions} options - Formatting options.
 * @returns {string[]} Array of formatted message strings.
 */
export function formatDiagnostics(messages, options = { kind: 'error', color: false }) {
  return esbuild.formatMessagesSync(messages, options);
}

/**
 * Analyzes build metafile.
 * @param {import('esbuild').Metafile} metafile - Build metafile object.
 * @param {import('esbuild').AnalyzeMetafileOptions} options - Analysis options.
 * @returns {string} Formatted metafile breakdown string.
 */
export function analyzeBuild(metafile, options = { verbose: false, color: false }) {
  return esbuild.analyzeMetafileSync(metafile, options);
}

export { esbuild };

import assert from 'node:assert';
import {
  esbuild,
  bundleInMemory,
  transformSource,
  formatDiagnostics,
  analyzeBuild,
} from '../src/index.mjs';

// 1. esbuild exports expected version 0.28.2
assert.strictEqual(esbuild.version, '0.28.2', 'esbuild version matches 0.28.2');

// 2. esbuild.buildSync bundles TypeScript source code into ESM in memory
const buildRes = bundleInMemory('export const calculate = (x: number, y: number): number => x * y + 10;', 'ts');
assert.strictEqual(buildRes.errors.length, 0, 'build completed with zero errors');
assert.strictEqual(buildRes.outputFiles.length, 1, 'build emitted one output file');
assert(buildRes.outputFiles[0].text.includes('calculate = (x, y) => x * y + 10'), 'bundle contains compiled function');

// 3. esbuild.transformSync transpiles JSX syntax to JavaScript with minification
const transformRes = transformSource('const View = () => <section><span>Active</span></section>;', {
  loader: 'jsx',
  minify: true,
});
assert.strictEqual(transformRes.warnings.length, 0, 'transform completed with zero warnings');
assert(transformRes.code.includes('React.createElement'), 'JSX converted to React.createElement');

// 4. esbuild.formatMessagesSync formats diagnostic error messages with file location and source line context
const formatted = formatDiagnostics([
  {
    text: 'Unexpected token in expression',
    location: {
      file: 'index.ts',
      line: 4,
      column: 12,
      lineText: 'const total = + ;',
    },
  },
], {
  kind: 'error',
  color: false,
});
assert.strictEqual(formatted.length, 1, 'formatted exactly one error message');
assert(formatted[0].includes('Unexpected token in expression'), 'formatted message includes error text');
assert(formatted[0].includes('index.ts:4:12'), 'formatted message includes file line and column');

// 5. esbuild.analyzeMetafileSync computes formatted bundle breakdown from build metafile
const metaBuild = esbuild.buildSync({
  stdin: {
    contents: 'const msg = "bundle meta test"; console.log(msg);',
    loader: 'js',
    resolveDir: process.cwd(),
  },
  metafile: true,
  write: false,
});
assert(metaBuild.metafile !== undefined, 'build generated metafile');
const analysis = analyzeBuild(metaBuild.metafile, {
  verbose: false,
  color: false,
});
assert(typeof analysis === 'string', 'metafile analysis returns string');
assert(analysis.length > 0, 'metafile analysis string is non-empty');

console.log('Contract tests passed successfully.');