| // META: global=window,worker |
| // 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'); |