FetchLoanDetailUseCaseTestCase2.dart

class LoanDetailResponse {
    final String _emi;

  LoanDetailResponse(this._emi);

   static from(EMICalculator emiCalculator) {
     return LoanDetailResponse(emiCalculator.calculateEMI().toString());
  }
}

class FetchLoanDetail extends UseCase<LoanParamRequest, LoanDetailResponse> {
  final ILoanRepository _loanRepository;

  FetchLoanDetail(this._loanRepository);

  @override
  Stream<LoanDetailResponse> buildUseCase(LoanParamRequest param) {
    return _loanRepository
        .getLoanFromServer(param.amount, param.time)
        .asStream()
        .map((loanDetailDTO) => LoanDetailResponse.from(EMICalculator(param.amount,loanDetailDTO._rate,param.time)));
  }
}