### Question:
DeviceGroup extends UserDefinedEntity { public Set<Device> getAllDevices() { Set<Device> allDevices = new HashSet<>(); for (Device device: devices) { device.setOnlyDeviceGroup(null); allDevices.add(device); } return Collections.unmodifiableSet(allDevices); } DeviceGroup(final String name);  DeviceGroup(final String name, final String description); protected  DeviceGroup(); static ScheduledJobInfo createDefaultScheduledJobInfo(); final Set<Device> getDevices(); final void addDevice(final Device device); final boolean removeDevice(final Device device); final boolean removeDevice(final String deviceName); final void setPeriodicReportDelayThreshold(final long milliseconds); final long getPeriodicReportDelayThreshold(); final void setEnablePeriodicReportDelayAlert(final boolean flag); final boolean isEnablePeriodicReportDelayAlert(); final void setOnDemandReportDelayThreshold(final long milliseconds); final long getOnDemandReportDelayThreshold(); final void setEnableOnDemandReportDelayAlert(final boolean flag); final boolean isEnableOnDemandReportDelayAlert(); boolean isWaitForAppraisalCompletionEnabled(); void setWaitForAppraisalCompletionEnabled(final boolean
                                                             waitForAppraisalCompletionEnabled); ScheduledJobInfo getScheduledJobInfo(); void setScheduledJobInfo(final ScheduledJobInfo scheduledJobInfo); HealthStatus getHealthStatus(); int getNumberOfDevices(); int getNumberOfTrustedDevices(); Set<Device> getAllDevices(); static final String DEFAULT_GROUP; static final long SECOND_MS_INTERVAL; static final long MINUTE_MS_INTERVAL; static final long FIVE_MINUTES_MS_INTERVAL; static final long HOUR_MS_INTERVAL; static final long DAY_MS_INTERVAL; static final long DEFAULT_REPORT_DELAY_THRESHOLD; static final long MINIMUM_PERIODIC_REPORT_INTERVAL; static final long MINIMUM_THRESHOLD_INTERVAL_MS; static final long DEFAULT_JOB_FREQUENCY_MS; }### Answer:
@Test public final void testGetAllDevices() throws Exception { Device device = DeviceTest.getTestDevice("TestDevice"); Device device2 = DeviceTest.getTestDevice("TestDevice2"); DeviceGroup deviceGroup = new DeviceGroup("TestDeviceGroup"); deviceGroup.addDevice(device); deviceGroup.addDevice(device2); Set<Device> devices = deviceGroup.getAllDevices(); Assert.assertEquals(devices.size(), 2); Assert.assertNull(devices.iterator().next().getDeviceGroup()); }