decompression-with-detach.tentative.window.js

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

// META: global=window,worker,shadowrealm

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

'use strict';

const kInputLength = 1000000;

async function createLargeCompressedInput() {

  const cs = new CompressionStream('deflate');

  // The input has to be large enough that it won't fit in a single chunk when

  // decompressed.

  const writer = cs.writable.getWriter();

  writer.write(new Uint8Array(kInputLength));

  writer.close();

  return concatenateStream(cs.readable);

promise_test(async () => {

  const input = await createLargeCompressedInput();

  const ds = new DecompressionStream('deflate');

  const writer = ds.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(ds.readable);

  // If output successfully decompressed and gave the right length, we can be

  // reasonably confident that no data corruption happened.

  assert_equals(

      output.byteLength, kInputLength, 'output should be the right length');

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