@Test
public void testExistsCompletion() {

    completeOperation(transactionProxy -> {
        doReturn(dataExistsReply(true)).when(mockActorContext).executeOperationAsync(
                any(ActorSelection.class), eqDataExists(), any(Timeout.class));
        transactionProxy.exists(TestModel.TEST_PATH);
        transactionProxy.exists(TestModel.TEST_PATH);
    });
}