### Question:
DockerUtil { public void reInitDockerClient() { LoggingService.logInfo(MODULE_NAME , "Start Docker Client re-initialization"); try { if (null != dockerClient) { dockerClient.close(); } } catch (IOException e) { logError(MODULE_NAME, "Docker client closing failed", new AgentSystemException(e.getMessage(), e)); } initDockerClient(); LoggingService.logInfo(MODULE_NAME , "Finished Docker Client re-initialization"); } private  DockerUtil(); static DockerUtil getInstance(); void reInitDockerClient(); String getDockerBridgeName(); void startContainer(Microservice microservice); void stopContainer(String id); void removeContainer(String id, Boolean withRemoveVolumes); @SuppressWarnings("deprecation") String getContainerIpAddress(String id); String getContainerName(Container container); String getContainerMicroserviceUuid(Container container); static String getIoFogContainerName(String microserviceUuid); Optional<Container> getContainer(String microserviceUuid); MicroserviceStatus getMicroserviceStatus(String containerId); List<Container> getRunningContainers(); List<Container> getRunningIofogContainers(); Optional<Statistics> getContainerStats(String containerId); long getContainerStartedAt(String id); boolean areMicroserviceAndContainerEqual(String containerId, Microservice microservice); Optional<String> getContainerStatus(String containerId); boolean isContainerRunning(String containerId); List<Container> getContainers(); void removeImageById(String imageId); @SuppressWarnings("resource") void pullImage(String imageName, String microserviceUuid, Registry registry); boolean findLocalImage(String imageName); String createContainer(Microservice microservice, String host); PruneResponse dockerPrune(); void update(PullResponseItem item, Map<String, ItemStatus> statuses);  }### Answer:
@Test public void testReInitDockerClient() { try { PowerMockito.doNothing().when(dockerClient).close(); dockerUtil.reInitDockerClient(); Mockito.verify(dockerClient).close(); Mockito.verify(dockerClientConfig, Mockito.atLeastOnce()).withDockerHost(any()); Mockito.verify(dockerClientConfig, Mockito.atLeastOnce()).withApiVersion(anyString()); verifyPrivate(dockerUtil, Mockito.atLeastOnce()).invoke("addDockerEventHandler"); } catch (Exception e) { fail("This should not happen"); } }