Function write

tests/unit/buffer.test.ts:428–431

(chunk, encoding, cb)

    const seen: string[] = [];
    const w = new Writable({
      write(chunk, encoding, cb) {
        seen.push(`${chunk.toString()}|${encoding}`);
        cb();
      },
    });
    await new Promise<void>((resolve) => {
      w.write("a");