### Question:
UserGroupAOImpl extends IRODSGenericAO implements UserGroupAO { @Override public List<User> listUserGroupMembers(final String userGroupName) throws JargonException { log.info("listUserGroupMembers()"); return listUserGroupMembers(userGroupName, ""); } protected  UserGroupAOImpl(final IRODSSession irodsSession, final IRODSAccount irodsAccount); @Override void addUserGroup(final UserGroup userGroup); @Override void addUserGroupAsGroupAdmin(final UserGroup userGroup); @Override void removeUserGroup(final String userGroupName); @Override void removeUserGroup(final UserGroup userGroup); @Override UserGroup find(final String userGroupId); @Override List<UserGroup> findAll(); @Override UserGroup findByName(final String userGroupName); @Override List<User> listUserGroupMembers(final String userGroupName); @Override List<User> listUserGroupMembers(final String userGroupName, final String targetZone); @Override List<UserGroup> findUserGroups(final String userGroupName); @Override List<UserGroup> findUserGroupsForUserInZone(final String userName, final String targetZone); @Override List<UserGroup> findUserGroupsForUser(final String userName); @Override boolean isUserInGroup(final String userName, final String groupName); @Override void addUserToGroup(final String userGroupName, final String userName, final String zoneName); @Override void addUserToGroupAsGroupAdmin(final String userGroupName, final String userName, final String zoneName); @Override void removeUserFromGroup(final String userGroupName, final String userName, final String zoneName); @Override List<UserGroup> findUserGroups(String userGroupName, boolean caseInsensitive); @Override List<String> findUserGroupNames(String userGroupName, boolean caseInsensitive);  }### Answer:
@Test public final void testListUserGroupMembersGroupNotExists() throws Exception { IRODSAccount irodsAccount = testingPropertiesHelper.buildIRODSAdminAccountFromTestProperties(testingProperties); String testUserGroup = "testListUserGroupMembersGroupNotExists"; IRODSAccessObjectFactory accessObjectFactory = irodsFileSystem.getIRODSAccessObjectFactory(); UserGroupAO userGroupAO = accessObjectFactory.getUserGroupAO(irodsAccount); List<User> users = userGroupAO.listUserGroupMembers(testUserGroup); Assert.assertTrue("no users should have been found", users.isEmpty()); }