compression-with-detach.tentative.window.js

Enable keyboard shortcuts

This WPT test may be referenced by the following Test IDs:
- /compression/compression-with-detach.tentative.window.html - WPT Dashboard Interop Dashboard

// META: global=window,worker,shadowrealm

// META: script=resources/concatenate-stream.js

'use strict';

const kInputLength = 500000;

function createLargeRandomInput() {

  const buffer = new ArrayBuffer(kInputLength);

  // The getRandomValues API will only let us get 65536 bytes at a time, so call

  // it multiple times.

  const kChunkSize = 65536;

  for (let offset = 0; offset < kInputLength; offset += kChunkSize) {

    const length =

        offset + kChunkSize > kInputLength ? kInputLength - offset : kChunkSize;

    const view = new Uint8Array(buffer, offset, length);

    crypto.getRandomValues(view);

  return new Uint8Array(buffer);

function decompress(view) {

  const ds = new DecompressionStream('deflate');

  const writer = ds.writable.getWriter();

  writer.write(view);

  writer.close();

  return concatenateStream(ds.readable);

promise_test(async () => {

  const input = createLargeRandomInput();

  const inputCopy = input.slice(0, input.byteLength);

  const cs = new CompressionStream('deflate');

  const writer = cs.writable.getWriter();

  writer.write(input);

  writer.close();

  // Object.prototype.then will be looked up synchronously when the promise

  // returned by read() is resolved.

  Object.defineProperty(Object.prototype, 'then', {

    get() {

      // Cause input to become detached and unreferenced.

      try {

        postMessage(undefined, 'nowhere', [input.buffer]);

      } catch (e) {

        // It's already detached.

});

  const output = await concatenateStream(cs.readable);

  // Perform the comparison as strings since this is reasonably fast even when

  // JITted JavaScript is running under an emulator.

  assert_equals(

      inputCopy.toString(), (await decompress(output)).toString(),

      'decompressing the output should return the input');

}, 'data should be correctly compressed even if input is detached partway');