### Question:
DBDeviceGroupManager extends DBManager<DeviceGroup> implements DeviceGroupManager { @Override public final DeviceGroup getDeviceGroup(final String name) throws DeviceGroupManagerException { LOGGER.debug("getting device group: {}", name); try { return super.get(name); } catch (DBManagerException e) { throw new DeviceGroupManagerException(e); } } DBDeviceGroupManager(final SessionFactory factory); @Override final DeviceGroup saveDeviceGroup(final DeviceGroup deviceGroup); @Override final void updateDeviceGroup(final DeviceGroup deviceGroup); @Override final Set<DeviceGroup> getDeviceGroupSet(); @Override final DeviceGroup getDeviceGroup(final String name); @Override final Set<DeviceGroup> getGroupsAssignedToPolicy(final Policy policy); @Override final boolean deleteDeviceGroup(final String name); @Override final FilteredRecordsList<DeviceGroup> getOrderedDeviceGroupList(
            final String columnToOrder, final boolean ascending, final int firstResult,
            final int maxResults, final String search);  }### Answer:
@Test public void testGetNull() { LOGGER.debug("testGetNull test started"); final DeviceGroupManager mgr = new DBDeviceGroupManager(sessionFactory); Assert.assertNull(mgr.getDeviceGroup(null)); }
@Test public void testGetUnknown() { LOGGER.debug("testGetUnknown test started"); final String unknown = "Some Unknown Device Group"; final DeviceGroupManager mgr = new DBDeviceGroupManager(sessionFactory); Assert.assertNull(mgr.getDeviceGroup(unknown)); }