Running

• In Starling Bank Developers Account, refresh or generate a new access token. Please replace bearer.token property in application.properties
• Run the project and do a GET call to localhost:8080/starling/round-up in Postman

The Challenge

We’d like you to develop a “round-up” feature for Starling customers using our public developer API that is available to all customers and partners.

For a customer, take all the transactions in a given week and round them up to the nearest pound. For example with spending of £4.35, £5.20 and £0.87, the round-up would be £1.58. This amount should then be transferred into a savings goal, helping the customer save for future adventures.

API calls

To make this work, the key parts from our public API you will need are:

1. Accounts - To retrieve accounts for the customer
2. Transaction feed - To retrieve transactions for the customer
3. Savings Goals - Create a savings goals and transfer money to savings goals

We do expect to see your working here: please do not use any of the libraries out there which provide an sdk for interacting with our api.

What to build

Pick your favourite platform to develop for. If you have experience with multiple languages that’s fantastic - you only need to submit for one and your choice won’t impact potential roles with us - we have plenty of engineers who work across platforms / learn news ones here!

Here’s what we imagine you will build for each platform, but you can diverge from this so long as you are prepared to explain what you’ve done and why:

• Java: Main method which runs the round up directly, or main method which starts an embedded web server with a REST resource we can invoke to trigger the round-up.

Thinking/Planning

• Get list of API Urls to use and test using Postman
• Create TransactionService to get List of Transaction to get transactions from the last week, using /feed/account/{accountUid}/settled-transactions-between endpoint and passing in arguments for dates by making call to /feed/account/{accountUid}/settled-transactions-between?minTransactionTimestamp={minTransactionTimestamp}&maxTransactionTimestamp={maxTransactionTimestamp}

e.g.
{
    "feedItems": [
        {
            "feedItemUid": "fd514cfd-cb3d-4e96-b024-abdd146fb371",
            "categoryUid": "bd96ee89-2bb9-4932-a34a-e8668ccff24b",
            "amount": {
                "currency": "GBP",
                "minorUnits": 3321
            },
            "sourceAmount": {
                "currency": "GBP",
                "minorUnits": 3321
            },
            "direction": "IN",
            "updatedAt": "2021-12-16T15:45:10.681Z",
            "transactionTime": "2021-12-16T15:45:10.000Z",
            "settlementTime": "2021-12-16T15:45:10.000Z",
            "source": "FASTER_PAYMENTS_IN",
            "status": "SETTLED",
            "counterPartyType": "SENDER",
            "counterPartyName": "Faster payment",
            "counterPartySubEntityName": "",
            "counterPartySubEntityIdentifier": "600522",
            "counterPartySubEntitySubIdentifier": "20025033",
            "reference": "Ref: 7295072450",
            "country": "GB",
            "spendingCategory": "INCOME",
            "hasAttachment": false,
            "hasReceipt": false
        },
        {
            "feedItemUid": "fd512b43-2b76-47ff-a31b-8edd340e19bc",
            "categoryUid": "bd96ee89-2bb9-4932-a34a-e8668ccff24b",
            "amount": {
                "currency": "GBP",
                "minorUnits": 3631
            },
            "sourceAmount": {
                "currency": "GBP",
                "minorUnits": 3631
            },
            "direction": "IN",
            "updatedAt": "2021-12-16T15:45:10.525Z",
            "transactionTime": "2021-12-16T15:45:10.000Z",
            "settlementTime": "2021-12-16T15:45:10.000Z",
            "source": "FASTER_PAYMENTS_IN",
            "status": "SETTLED",
            "counterPartyType": "SENDER",
            "counterPartyName": "Faster payment",
            "counterPartySubEntityName": "",
            "counterPartySubEntityIdentifier": "600522",
            "counterPartySubEntitySubIdentifier": "20025033",
            "reference": "Ref: 9246109671",
            "country": "GB",
            "spendingCategory": "INCOME",
            "hasAttachment": false,
            "hasReceipt": false
        }
}

• Create RoundUpService where bulk of processing will take place
  • Create RoundUp class to loop through Transaction items and total up the change left over from the minorUnits of the Amount
• Create SavingGoalService to add savings to savings goal using /account/{accountUid}/savings-goals and /account/{accountUid}/savings-goals/{savingsGoalUid}/add-money/{transferUid}. If no goal exists, create one and add the amount to it

E.g. list of empty savings goals
{
    "savingsGoalList": []
}

E.g. populated savings goals
{
    "savingsGoalList": [
        {
            "savingsGoalUid": "d3ecb50c-8ff0-41bc-bc66-f40df9dd78d4",
            "name": "My savings goal 0.6195278725379234",
            "target": {
                "currency": "GBP",
                "minorUnits": 100000
            },
            "totalSaved": {
                "currency": "GBP",
                "minorUnits": 545
            },
            "savedPercentage": 0
        }
    ]
}

• Return updated list of savings goal

• Get AccountUID from /accounts endpoint and pass through account id to services for making calls

E.g. account response
{
    "accounts": [
        {
            "accountUid": "32af7fea-cc61-4cac-80b4-20aa52a77445",
            "accountType": "PRIMARY",
            "defaultCategory": "bd96ee89-2bb9-4932-a34a-e8668ccff24b",
            "currency": "GBP",
            "createdAt": "2021-12-16T15:44:19.655Z",
            "name": "Personal"
        }
    ]
}

Result