mokosh/tests/background/sw-bundle-import.test.ts

// tests/background/sw-bundle-import.test.ts
//
// Tier-1 SW-bundle-loadability gate (Debug session 01-08-sw-incompatibility).
//
// This test closes the orchestrator-side gap that produced the 01-08 init
// crash: prior to this gate, the only SW-compat assertion was
// `tests/background/webm-remux-deps.test.ts`, which loaded the SOURCE
// packages (`ts-ebml`, `webm-muxer`) under default Node globals. That test
// passed because the raw packages import fine in Node — but it never
// loaded the BUNDLED output emitted by `vite build`, and Vite's CJS-interop
// pipeline tree-shook the transitive `ebml` package out of the bundle while
// leaving a dangling destructure reference (`{tools:f}=Pc` against an empty
// placeholder `Pc`). The result: SW dies at top-level module init with
// `TypeError: Cannot read properties of undefined (reading 'readVint')`
// before any handler can register, and the operator's chrome://extensions
// "service worker" link goes inaccessible.
//
// This test exercises the actual built artifact under SW-simulated globals
// (Buffer/process/document/window stripped). Any throw at top-level module
// evaluation surfaces as a clean test failure with the exact stack the
// operator would see in Chrome.
//
// Implementation note: the strip+import happens in a SPAWNED Node child
// process, not in-process. Vitest's own RPC layer references both `Buffer`
// (`node_modules/vitest/dist/chunks/rpc.*.js`) and `process.nextTick`, so
// stripping those on the test runner's globalThis crashes vitest itself.
// A child process gives us a fresh V8 isolate where we can strip cleanly.
//
// Pre-flight contract: callers must `npm run build` first. The test fails
// fast with a clear "run npm run build" message if `dist/` is missing.
//
// Per `feedback-pre-checkpoint-bundle-gates.md` (auto-loaded memory): any
// future plan executor whose work surfaces a SW must run this test before
// any operator-empirical checkpoint.
//
// Reference for SW-restricted globals:
//   https://developer.mozilla.org/en-US/docs/Web/API/ServiceWorkerGlobalScope
// Reference for Node ESM dynamic-import accepting file:// URLs:
//   https://nodejs.org/api/esm.html#import-expressions
// Reference for `child_process.execFile`:
//   https://nodejs.org/api/child_process.html#child_processexecfilefile-args-options-callback

import { execFile } from 'node:child_process';
import { existsSync, readFileSync } from 'node:fs';
import { resolve as resolvePath } from 'node:path';
import { pathToFileURL } from 'node:url';
import { promisify } from 'node:util';

import { describe, expect, it } from 'vitest';

const execFileAsync = promisify(execFile);

// Globals stripped to simulate the MV3 Service Worker runtime. Service
// Workers expose ServiceWorkerGlobalScope which has NO `window`, NO
// `document`, NO `Buffer`, and NO `process`. They DO have standard
// browser-ish globals (fetch, Blob, Crypto, etc.) which Node provides
// natively in modern versions, so we don't strip those.
const SW_FORBIDDEN_GLOBALS: ReadonlyArray<string> = [
  'window',
  'document',
  'Buffer',
  'process',
];

// Sentinel strings emitted by the child process; checked by the parent
// to distinguish success from failure without resorting to exit codes
// (the child may exit 0 on a caught throw).
const CHILD_OK_SENTINEL = '__SW_BUNDLE_IMPORT_OK__';
const CHILD_FAIL_SENTINEL = '__SW_BUNDLE_IMPORT_FAILED__';

// Cap how long the child has to import. Real SW init takes < 1 s; if the
// import takes longer than this, treat it as a hang (functionally the
// same as a top-level throw from the operator's perspective).
const CHILD_TIMEOUT_MS = 10_000;

interface ChildImportResult {
  readonly ok: boolean;
  readonly errorMessage: string;
  readonly errorStackFirstLine: string;
}

/**
 * Resolve the file:// URL of the built SW chunk by parsing the
 * `dist/service-worker-loader.js` shim that crxjs emits. The shim is a
 * one-liner of the form `import './assets/index.ts-<hash>.js';` whose hash
 * changes per build; parsing it avoids hard-coding a content hash that
 * would break on every rebuild.
 *
 * @returns Absolute file:// URL of the SW chunk, ready for dynamic import.
 * @throws If `dist/` is missing or the loader shim cannot be parsed.
 */
function resolveBuiltSwChunkUrl(): string {
  const distDir = resolvePath(process.cwd(), 'dist');
  const loaderPath = resolvePath(distDir, 'service-worker-loader.js');

  if (!existsSync(loaderPath)) {
    throw new Error(
      `dist/service-worker-loader.js not found at ${loaderPath}. ` +
        `Run \`npm run build\` before running this test.`,
    );
  }

  const loaderSource = readFileSync(loaderPath, 'utf8');
  // crxjs emits exactly: `import './assets/index.ts-<hash>.js';\n`
  const importMatch = loaderSource.match(/^\s*import\s+['"](.+?)['"]\s*;?\s*$/m);
  if (importMatch === null) {
    throw new Error(
      `Could not parse SW import path from service-worker-loader.js. ` +
        `Loader content was: ${JSON.stringify(loaderSource)}`,
    );
  }

  const chunkRelativePath = importMatch[1];
  const chunkAbsolutePath = resolvePath(distDir, chunkRelativePath);
  return pathToFileURL(chunkAbsolutePath).href;
}

/**
 * Build the inline ESM source that the spawned child will execute. The
 * child strips the listed globals on its own isolate and then dynamically
 * imports the SW chunk, reporting back via stdout sentinels.
 *
 * Kept as a function (not a template literal at module top) so the
 * sentinel/global lists stay synced with the constants above.
 *
 * @param chunkUrl - file:// URL the child will import.
 * @returns ESM source the child runs under `node --input-type=module`.
 */
function buildChildSource(chunkUrl: string): string {
  const stripLines = SW_FORBIDDEN_GLOBALS.map(
    (key) => `delete globalThis['${key}'];`,
  ).join(' ');
  return [
    stripLines,
    `try {`,
    `  await import(${JSON.stringify(chunkUrl)});`,
    `  console.log(${JSON.stringify(CHILD_OK_SENTINEL)});`,
    `} catch (e) {`,
    `  const msg = e && e.message ? String(e.message) : String(e);`,
    `  const stack = e && e.stack ? String(e.stack).split('\\n')[0] : '(no stack)';`,
    `  console.log(${JSON.stringify(CHILD_FAIL_SENTINEL)});`,
    `  console.log('MSG:' + msg);`,
    `  console.log('STK:' + stack);`,
    `}`,
  ].join(' ');
}

/**
 * Spawn a Node child process that imports the SW chunk under stripped
 * globals and returns the result. Resolves rather than rejects on import
 * failure — the failure is the data the test asserts on.
 *
 * @param chunkUrl - file:// URL the child will import.
 * @returns Structured result; `ok: false` means the bundle threw.
 */
async function runSwBundleImportInChild(chunkUrl: string): Promise<ChildImportResult> {
  const source = buildChildSource(chunkUrl);
  const { stdout } = await execFileAsync(
    process.execPath,
    ['--input-type=module', '-e', source],
    {
      timeout: CHILD_TIMEOUT_MS,
      maxBuffer: 4 * 1024 * 1024,
    },
  );

  if (stdout.includes(CHILD_OK_SENTINEL)) {
    return { ok: true, errorMessage: '', errorStackFirstLine: '' };
  }

  if (stdout.includes(CHILD_FAIL_SENTINEL)) {
    const msgMatch = stdout.match(/^MSG:(.*)$/m);
    const stkMatch = stdout.match(/^STK:(.*)$/m);
    return {
      ok: false,
      errorMessage: msgMatch?.[1] ?? '(no message)',
      errorStackFirstLine: stkMatch?.[1] ?? '(no stack)',
    };
  }

  throw new Error(
    `Child process produced neither OK nor FAIL sentinel. ` +
      `stdout was: ${JSON.stringify(stdout)}`,
  );
}

describe('SW bundle loadability (Tier-1 gate — closes the 01-08 orchestrator gap)', () => {
  // Resolved at module-level (BEFORE the spawn) so `process.cwd()` and
  // `process.execPath` are still available.
  const swChunkUrl = resolveBuiltSwChunkUrl();

  it('built SW chunk imports without throwing under SW-simulated globals', async () => {
    const result = await runSwBundleImportInChild(swChunkUrl);

    expect(
      result.ok,
      result.ok
        ? 'unreachable'
        : `Built SW bundle throws at top-level module init under ` +
            `SW-simulated globals (${SW_FORBIDDEN_GLOBALS.join(', ')} ` +
            `stripped). This is exactly what kills the SW in Chrome and ` +
            `makes chrome://extensions "service worker" inaccessible.\n\n` +
            `First line of stack: ${result.errorStackFirstLine}\n` +
            `Full message: ${result.errorMessage}\n\n` +
            `Bundle URL: ${swChunkUrl}`,
    ).toBe(true);
  });
});