@Test
public void testRequestNotify() {

  ApiStreamObserver<String> requestStream =
      tracedCallable.clientStreamingCall(outerResponseObsever, callContext);
  requestStream.onNext("request1");
  requestStream.onNext("request2");
  innerCallable.responseObserver.onNext("response");
  innerCallable.responseObserver.onCompleted();
  verify(tracer, times(2)).requestSent();
  assertThat(outerResponseObsever.completed).isTrue();
  assertThat(innerCallable.requestObserver.messages).containsExactly("request1", "request2");
}