// Ensure exceeding the high watermark makes channel unwritable.
ch.write(buffer().writeZero(128));
assertThat(buf.toString(), is("false "));
// Ensure going down to the low watermark makes channel writable again by flushing the first write.
assertThat(ch.unsafe().outboundBuffer().remove(), is(true));
assertThat(ch.unsafe().outboundBuffer().totalPendingWriteBytes(), is(128L));
assertThat(buf.toString(), is("false true "));
safeClose(ch);
}