compression-including-empty-chunk.tentative.any.js

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// META: script=third_party/pako/pako_inflate.min.js

// META: timeout=long

'use strict';

// This test asserts that compressing '' doesn't affect the compressed data.

// Example: compressing ['Hello', '', 'Hello'] results in 'HelloHello'

async function compressChunkList(chunkList, format) {

  const cs = new CompressionStream(format);

  const writer = cs.writable.getWriter();

  for (const chunk of chunkList) {

    const chunkByte = new TextEncoder().encode(chunk);

    writer.write(chunkByte);

  const closePromise = writer.close();

  const out = [];

  const reader = cs.readable.getReader();

  let totalSize = 0;

  while (true) {

    const { value, done } = await reader.read();

    if (done)

      break;

    out.push(value);

    totalSize += value.byteLength;

  await closePromise;

  const concatenated = new Uint8Array(totalSize);

  let offset = 0;

  for (const array of out) {

    concatenated.set(array, offset);

    offset += array.byteLength;

  return concatenated;

const chunkLists = [

  ['', 'Hello', 'Hello'],

  ['Hello', '', 'Hello'],

  ['Hello', 'Hello', '']

];

const expectedValue = new TextEncoder().encode('HelloHello');

for (const chunkList of chunkLists) {

  promise_test(async t => {

    const compressedData = await compressChunkList(chunkList, 'deflate');

    // decompress with pako, and check that we got the same result as our original string

    assert_array_equals(expectedValue, pako.inflate(compressedData), 'value should match');

  }, `the result of compressing [${chunkList}] with deflate should be 'HelloHello'`);

  promise_test(async t => {

    const compressedData = await compressChunkList(chunkList, 'gzip');

    // decompress with pako, and check that we got the same result as our original string

    assert_array_equals(expectedValue, pako.inflate(compressedData), 'value should match');

  }, `the result of compressing [${chunkList}] with gzip should be 'HelloHello'`);

  promise_test(async t => {

    const compressedData = await compressChunkList(chunkList, 'deflate-raw');

    // decompress with pako, and check that we got the same result as our original string

    assert_array_equals(expectedValue, pako.inflateRaw(compressedData), 'value should match');

  }, `the result of compressing [${chunkList}] with deflate-raw should be 'HelloHello'`);