clientReaderWithCompression.processNextFrame()
    }.also { expected ->
      assertThat(expected.message).isEqualTo("Unexpected rsv1 flag")
    }
  }

  @Test fun reservedFlags2and3AreUnsupported() {
    data.write("aa00".decodeHex()) // Empty pong, flag 2 set.
    assertFailsWith<ProtocolException> {
      clientReader.processNextFrame()
    }.also { expected ->