this.tree = getOrCreateTree();
tree = this.signet.getTree(Constants.TREE_ID);
  public Fixtures(Signet signet)  throws  	OperationNotSupportedException,  	TreeNotFoundException,  	SignetAuthorityException,  	ObjectNotFoundException  {    super();    this.signet = signet;        for (int i = 0; i < Constants.MAX_SUBJECTS; i++)    {      Subject subject = getOrCreateSubject(i);      signet.save(subject);    }        this.subsystem = getOrCreateSubsystem();        this.tree = getOrCreateTree();    this.subsystem.setTree(this.tree);        for (int i = 0; i < Constants.MAX_CATEGORIES; i++)    {      Category category = getOrCreateCategory(i);     }        for (int i = 0; i < Constants.MAX_CHOICE_SETS; i++)    {      ChoiceSet choiceSet = getOrCreateChoiceSet(i);     }        for (int i = 0; i < Constants.MAX_LIMITS; i++)    {      Limit limit = getOrCreateLimit(i);    }        for (int i = 0; i < Constants.MAX_FUNCTIONS; i++)    {      Function function = getOrCreateFunction(i);    }        for (int permissionNum = 0;         permissionNum < Constants.MAX_PERMISSIONS;         permissionNum++)    {      Permission permission = getOrCreatePermission(permissionNum);            // Permission 0 is associated with Limit 0 and Function 0,      // Permission 1 is associated with Limits 0 and 1 and Function 1,      // and so on.      getOrCreateFunction(permissionNum).addPermission(permission);            for (int limitNum = 0; limitNum <= permissionNum; limitNum++)      {        permission.addLimit(getOrCreateLimit(limitNum));      }    }        signet.save(this.subsystem);        for (int i = 0; i < Constants.MAX_SUBJECTS; i++)    {      Assignment assignment = getOrCreateAssignment(i);      this.signet.save(assignment);    }        // This is intended to create an Assignment for Subject 0 that can    // be edited by Subject 2, but does not allow Subject 0 to edit the    // similar (but using different Limit-values) Assignment held by    // Subject 2.    int[] limitChoiceNumbers = {0, 0, 0};    Assignment assignment    	= getOrCreateAssignment    			(0,  // subject-number    			 2,  // function-number    			 limitChoiceNumbers);    this.signet.save(assignment);  }