我无法发表评论...但是也许您可以看看这个post。它不是相同的语言，但看起来却是相同的行为。

祝你好运。

在这里确定我的问题的解决方案：

提取/检索数据

final Either<ServerException,TokenModel> result = await repository.getToken(...);
result.fold(
 (exception) => DoWhatYouWantWithException,(tokenModel) => DoWhatYouWantWithModel
);

//Other way to 'extract' the data
if (result.isRight()) {
  final TokenModel tokenModel = result.getOrElse(null);
}

测试异常

//You can extract it from below,or test it directly with the type
expect(() => result,throwsA(isInstanceOf<ServerException>()));

  Future<Either<Failure,FactsBase>> call(Params params) async {
final resulting = await repository.facts();
return resulting.fold(
  (failure) {
    return Left(failure);
  },(factsbase) {
    DateTime cfend = sl<EndDateSetting>().finish;        
    List<CashAction> actions = factsbase.transfers.process(facts: factsbase,startDate: repository.today,finishDate: cfend); // process all the transfers in one line using extensions
    actions.addAll(factsbase.transactions.process(facts: factsbase,finishDate: cfend));
    for(var action in actions) action.account.cashActions.add(action); // copy all the CashActions to the Account.
    for(var account in factsbase.accounts) account.process(start: repository.today);
    return Right(factsbase);
  },);

}