/** For testing: sends a ping to be awaited with [awaitPong]. */
  @Throws(InterruptedException::class)
  fun writePing() {
    withLock {
      awaitPingsSent++
    }

    // 0x4f 0x4b 0x6f 0x6b is "OKok".
    writePing(false, AWAIT_PING, 0x4f4b6f6b)
  }

  /** For testing: awaits a pong. */
  @Throws(InterruptedException::class)
  fun awaitPong() {
    withLock {

    assertThat(pingFrame.streamId).isEqualTo(0)
    assertThat(pingFrame.payload1).isEqualTo(Http2Connection.AWAIT_PING)
    assertThat(pingFrame.payload2).isEqualTo(0x4f4b6f6b) // OKok.
    assertThat(pingFrame.ack).isFalse()
  }

  @Test fun unexpectedPongIsNotReturned() {
    // Write the mocking script.
    peer.sendFrame().settings(Settings())
    peer.acceptFrame() // ACK