@Test
public void testSyncError() {

  RuntimeException expectedError = new RuntimeException("fake error");
  innerCallable.syncError = expectedError;
  try {
    tracedCallable.clientStreamingCall(outerResponseObsever, callContext);
  } catch (RuntimeException e) {
    // noop
  }
  verify(tracer, times(1)).operationFailed(expectedError);
}