* exceptions thrown from the test do not cause this check to fail.
   */
  @RegisterExtension
  val noDataLeftBehind =
    AfterEachCallback { context: ExtensionContext ->
      if (context.executionException.isPresent) return@AfterEachCallback
      assertThat(data.readByteString().hex(), "Data not empty")
        .isEqualTo("")
    }

  // Mutually exclusive. Use the one corresponding to the peer whose behavior you wish to test.