Transfer Service

transfer-service.js

class TransferService {
async transfer({ id, sender, receiver, transferAmount, bankName }) {
    // Validation
    if (!sender || !receiver || !transferAmount || !bankName) {
      throw new Error("Some mandatory property was not provided");
    }
  
    // Handle insufficient credit
    if (this.options.creditPolicy === "zero" && sender.credit < transferAmount) {
      this.numberOfDeclined++; //incrementing interal metric
      return {id, status: "declined",date};
    }

    // All good, let's transfer using the bank 3rd party service + save in DB
    await this.bankProviderService.transfer(sender, receiver, transferAmount, bankName);
    await this.repository.save({id,sender,receiver,transferAmount,bankName});

    return {id,status: "approved", date: new Date()};
  }  
  
  getTransfers(senderName){
    // Query the DB
  }
}

I should you should move line 17 to the end of 16 to decrease confusion

maybe also await the transfer and save call