}
  }

  @Test fun closeReservedThrows() {
    assertFailsWith<IllegalArgumentException> {
      clientWriter.writeClose(1005, "Hello".encodeUtf8())
    }.also { expected ->
      assertThat(expected.message).isEqualTo("Code 1005 is reserved and may not be used.")
    }
  }

  @Test fun serverEmptyPing() {
    serverWriter.writePing(EMPTY)
    assertData("8900")
  }

  internal const val CLOSE_CLIENT_GOING_AWAY = 1001

  /** Used when an empty close frame was received (i.e., without a status code). */
  internal const val CLOSE_NO_STATUS_CODE = 1005

  fun toggleMask(
    cursor: Buffer.UnsafeCursor,
    key: ByteArray,
  ) {
    var keyIndex = 0
    val keyLength = key.size
    do {
      val buffer = cursor.data
      var i = cursor.start

   1D18C-1D1A9
   1D1AE-1D1DD
   1D400-1D454
   1D456-1D49C
   1D49E-1D49F
   1D4A2
   1D4A5-1D4A6
   1D4A9-1D4AC
   1D4AE-1D4B9
   1D4BB
   1D4BD-1D4C0
   1D4C2-1D4C3
   1D4C5-1D505
   1D507-1D50A
   1D50D-1D514
   1D516-1D51C
   1D51E-1D539
   1D53B-1D53E
   1D540-1D544
   1D546
   1D54A-1D550
   1D552-1D6A3
   1D6A8-1D7C9
   20000-2A6D6
   2F800-2FA1D