apply {
      actions += { stream ->
        val actual = stream.requestBody.readUtf8(expected.utf8Size())
        if (actual != expected) throw AssertionError("$actual != $expected")
      }
    }

  fun exhaustRequest() =
    apply {
      actions += { stream ->
        if (!stream.requestBody.exhausted()) throw AssertionError("expected exhausted")
      }
    }

  fun cancelStream() =
    apply {