PreyeaRegmi

class EMICalculator {

  final double amount, rate, time;
  EMICalculator(this.amount, this.rate, this.time);

  double calculateEMI()
  {
    return amount*rate*(1 + rate)*time/((1+rate)*time-1);
  }
}

PreyeaRegmi

void main()
{
  test("EMI cannot be zero",()
  {
    EMICalculator emiCalculator=EMICalculator(1,2,3);
    //Performing assertion
    expect(emiCalculator.calculateEMI(),greaterThan(0),reason:"EMI calculated is zero");
  });
}

PreyeaRegmi

//Domain Entity responsible for calculating EMI for given params.
class EMICalculator {

  final double amount, rate, time;
  EMICalculator(this.amount, this.rate, this.time);

  double calculateEMI()
  {
    return -1;
  }

PreyeaRegmi

void main()
{

  test("Amount cannot be null",()
  {
    EMICalculator emiCalculator=EMICalculator(1,2,3);
    //Performing assertion
    expect(emiCalculator.amount,isNot(null), reason:"Amount cannot be null");
  });

PreyeaRegmi

//Domain Entity responsible for calculating EMI for given params.
class EMICalculator {  
  final double amount, rate, time;
  EMICalculator(this.amount, this.rate, this.time);  
}

PreyeaRegmi

void main()
{

  test("Amount cannot be null",()
  {
    EMICalculator emiCalculator=EMICalculator();
    //Performing assertion
    expect(emiCalculator.amount,isNot(null), reason:"Amount cannot be null");
  });

PreyeaRegmi

//Domain Entity responsible for calculating EMI for given params.
class EMICalculator
{
    double? amount,rate,time;
}

PreyeaRegmi

//Usecase Implementation
class ValidateBillingAndShippingAddressUseCase extends UseCase<
    BillingAndShippingAddressValidationRequest,
    BillingAndShippingAddressValidationResponse> {
  final AddressRespository _addressRespository;

  ValidateBillingAndShippingAddressUseCase(this._addressRespository);

  @override
  Stream<BillingAndShippingAddressValidationResponse> buildUseCase(

PreyeaRegmi

  //Usecase Implementation
  class PostBillingInfoUseCase
    extends UseCase<BillingInfoRequest, BillingInfoResponse> {
  final BillingInfoRepository _billingInfoRepository;

  PostBillingInfoUseCase(this._billingInfoRepository);

  @override
  Stream<BillingInfoResponse> buildUseCase(BillingInfoRequest param) {
    return _billingInfoRepository.postBillingInfo(param).asStream();

PreyeaRegmi

abstract class BaseUseCase<P, R> {

  Stream<R> buildUseCase(P param);

  StreamSubscription<R> execute(P param,void Function(R) result,void Function(String) error)
  {
    return buildUseCase(param).listen(result,onError: (Object exception, StackTrace stackTrace){
      error(exception.toString());
    });
  }