@Test
public void testOperationFinish() {

  tracedCallable.call("test", responseObserver, callContext);
  MockServerStreamingCall<String, String> innerCall = innerCallable.popLastCall();
  innerCall.getController().getObserver().onComplete();
  assertThat(responseObserver.isDone()).isTrue();
  verify(tracer, times(1)).operationSucceeded();
}