assertThat(event.response).isNull()
    assertThat(event.t).isSameAs(t)
  }

  fun assertFailure(
    cls: Class<out IOException?>?,
    vararg messages: String,
  ) {
    val event = nextEvent() as Failure
    assertThat(event.response).isNull()
    assertThat(event.t.javaClass).isEqualTo(cls)
    if (messages.isNotEmpty()) {
      assertThat(messages).contains(event.t.message)
    }
  }