lightningcss 1.33.0: bundle

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 bundle in pkg:npm/lightningcss@1.33.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/lightningcss@1.33.0
Demonstrate these symbols/APIs:
  - bundle

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.

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@import "./vars.css";

.card {
  background: var(--main-bg);
  padding: 10px;
}

@import "./reset.css";
@import "./components.css";

body {
  margin: 0;
}

@import "./non-existent-subfile.css";

.test {
  color: red;
}

.btn {
  color: blue;
}

@import "./module-button.css";

.container {
  display: flex;
}

* {
  box-sizing: border-box;
}

.box {
  user-select: none;
  display: flex;
}

:root {
  --main-bg: #fff;
}

{
  "name": "sample-lightningcss-bundle",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-lightningcss-bundle",
      "version": "1.0.0",
      "dependencies": {
        "lightningcss": "1.33.0"
      }
    },
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      "license": "Apache-2.0",
      "engines": {
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      }
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      "version": "1.33.0",
      "resolved": "https://registry.npmjs.org/lightningcss/-/lightningcss-1.33.0.tgz",
      "integrity": "sha512-WkUDrojuJs0xkgGf2udWxa3yGBRxPtxUkB79i6aCZLRgc7PM8fZe9TosfPDcvEpQZbuFASnHYmRLBLUbmLOIIA==",
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      "dependencies": {
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      "funding": {
        "type": "opencollective",
        "url": "https://opencollective.com/parcel"
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}

{
  "name": "sample-lightningcss-bundle",
  "version": "1.0.0",
  "private": true,
  "dependencies": {
    "lightningcss": "1.33.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify bundle in pkg:npm/lightningcss@1.33.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/lightningcss@1.33.0"
  ],
  "symbols": [
    "bundle"
  ]
}

const assert = require('node:assert/strict');
const path = require('node:path');
const { bundle, browserslistToTargets } = require('lightningcss');

const fixturesDir = path.join(__dirname, '..', 'fixtures');

// 1. bundle inlines nested @import rules into a single CSS output
{
  const entryPath = path.join(fixturesDir, 'main.css');
  const result = bundle({
    filename: entryPath,
  });

  const css = result.code.toString();
  assert.ok(css.includes('box-sizing: border-box;'), 'Should include reset styles');
  assert.ok(css.includes('--main-bg: #fff;'), 'Should include variable definitions');
  assert.ok(css.includes('background: var(--main-bg);'), 'Should include component styles');
  assert.ok(css.includes('margin: 0;'), 'Should include body styles');
  assert.ok(!css.includes('@import'), 'All @import statements should be inlined');
}

// 2. bundle minifies bundled CSS output when minify option is true
{
  const entryPath = path.join(fixturesDir, 'main.css');
  const result = bundle({
    filename: entryPath,
    minify: true,
  });

  const css = result.code.toString();
  assert.equal(css.includes('\n'), false, 'Minified CSS should not contain newlines');
  assert.ok(css.includes('*{box-sizing:border-box}'), 'Should minify reset rule');
  assert.ok(css.includes(':root{--main-bg:#fff}'), 'Should minify root variables');
  assert.ok(css.includes('.card{background:var(--main-bg);padding:10px}'), 'Should minify card rule');
  assert.ok(css.includes('body{margin:0}'), 'Should minify body rule');
}

// 3. bundle generates source map when sourceMap option is true
{
  const entryPath = path.join(fixturesDir, 'main.css');
  const result = bundle({
    filename: entryPath,
    sourceMap: true,
  });

  assert.ok(Buffer.isBuffer(result.map), 'result.map should be a Buffer');
  const map = JSON.parse(result.map.toString());
  assert.equal(map.version, 3, 'Source map version should be 3');
  assert.ok(Array.isArray(map.sources), 'Source map should contain sources array');
  assert.ok(map.sources.some((s) => s.endsWith('main.css')), 'Sources should contain main.css');
  assert.ok(map.sources.some((s) => s.endsWith('reset.css')), 'Sources should contain reset.css');
  assert.ok(map.sources.some((s) => s.endsWith('vars.css')), 'Sources should contain vars.css');
  assert.ok(map.sources.some((s) => s.endsWith('components.css')), 'Sources should contain components.css');
}

// 4. bundle generates scoped CSS class names and exports mapping when cssModules option is true
{
  const entryPath = path.join(fixturesDir, 'module-entry.css');
  const result = bundle({
    filename: entryPath,
    cssModules: true,
  });

  assert.ok(result.exports, 'result.exports should be defined');
  assert.ok(result.exports.container, 'result.exports should contain container export');
  assert.ok(typeof result.exports.container.name === 'string', 'container name should be a string');
  assert.ok(result.exports.container.name.includes('container'), 'container name should include local name');
  const css = result.code.toString();
  assert.ok(css.includes(result.exports.container.name), 'Bundled CSS should contain scoped class name');
}

// 5. bundle lowers CSS syntax according to specified browser targets
{
  const entryPath = path.join(fixturesDir, 'target.css');
  const result = bundle({
    filename: entryPath,
    targets: browserslistToTargets(['ie 11']),
    minify: true,
  });

  const css = result.code.toString();
  assert.ok(css.includes('-ms-user-select:none'), 'Should prefix user-select for IE 11');
  assert.ok(css.includes('user-select:none'), 'Should include standard user-select');
}

// 6. bundle throws an error when an imported file cannot be resolved
{
  const entryPath = path.join(fixturesDir, 'missing-import.css');
  assert.throws(
    () => {
      bundle({
        filename: entryPath,
      });
    },
    (err) => {
      return err instanceof Error && (err.name === 'SyntaxError' || err.message.includes('No such file') || err.data === 'ResolverError');
    },
    'Should throw error when imported file does not exist'
  );
}

// 7. bundle throws an error when entry file does not exist
{
  const entryPath = path.join(fixturesDir, 'does-not-exist.css');
  assert.throws(
    () => {
      bundle({
        filename: entryPath,
      });
    },
    (err) => {
      return err instanceof Error && (err.name === 'SyntaxError' || err.message.includes('No such file') || err.data === 'ResolverError');
    },
    'Should throw error when entry file does not exist'
  );
}