### Question:
DockerUtil { public String getContainerName(Container container) { return container.getNames()[0].substring(1); } 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 testGetContainerName() { assertEquals("iofog_containerName1", dockerUtil.getContainerName(container)); }
@Test public void testGetContainerNameWhenThereIsNoContainer() { String[] containers = {" "}; PowerMockito.when(container.getNames()).thenReturn(containers); assertEquals("", dockerUtil.getContainerName(container)); }