### Question:
PipelineExecutorTaskManagerImplHelper { public List<PipelineEventListener> createExternalListeners() { List<PipelineEventListener> eventListeners = new ArrayList<>(); pipelineEventListenerInstance.iterator().forEachRemaining(eventListeners::add); return eventListeners; } PipelineExecutorTaskManagerImplHelper(final Instance<ConfigExecutor> configExecutorInstance,
                                                 final Instance<PipelineEventListener> pipelineEventListenerInstance); ExecutorService createExecutorService(); PipelineExecutor createPipelineExecutor(); List<PipelineEventListener> createExternalListeners(); void notifyExternalListeners(final List<PipelineEventListener> externalListeners,
                                        final PipelineEvent event); PipelineExecutorTaskImpl createTask(final PipelineExecutorTaskDef taskDef); PipelineExecutorTaskImpl createTask(final PipelineExecutorTaskDef taskDef,
                                               final String executionId); String generateTaskId(); void setTaskInStoppedStatus(final PipelineExecutorTaskImpl task);  }### Answer:
@Test public void testCreateExternalListeners() { List<PipelineEventListener> result = taskManagerHelper.createExternalListeners(); verify(eventListenersInstance, times(1)).iterator(); assertEquals(externalListeners, result); }