kata-SG

Bank account kata

Think of your personal bank account experience. When in doubt, go for the simplest solution.

Requirements

• Deposit and Withdrawal
• Account statement (date, amount, balance)
• Statement printing

The expected result is a service API, and its underlying implementation, that meets the expressed needs.
Nothing more, especially no UI, no persistence.

User Stories

US 1:

In order to save money
As a bank client
I want to make a deposit in my account

US 2:

In order to retrieve some or all of my savings
As a bank client
I want to make a withdrawal from my account

US 3:

In order to check my operations
As a bank client
I want to see the history (operation, date, amount, balance) of my operations

Solution

Exposed REST API with the following endpoints

feature	verb	url	request body	response
Save/Withdraw	POST	/accounts/{accountId}	{ "amount": 10, "type": "SAVE" }	{"result":"SUCCESSFUL","message":"Amount of 10$ successfully deposited in your account","balance":29}
Retrieve	GET	/accounts/{accountId}	NA	{"operations":[{"type":"SAVE","amount":10,"balance":10,"date":"2023-06-12"},{"type":"WITHDRAW","amount":1,"balance":9,"date":"2023-06-14"}]}

Examples

View account history

curl http://localhost:8080/bank-service/api/v1/accounts/ACCOUNT_001

{
  "operations": [
    {
      "type": "SAVE",
      "amount": 10,
      "balance": 10,
      "date": "2023-06-12"
    },
    {
      "type": "WITHDRAW",
      "amount": 1,
      "balance": 9,
      "date": "2023-06-14"
    },
    {
      "type": "SAVE",
      "amount": 10,
      "balance": 19,
      "date": "2023-06-15"
    },
    {
      "type": "SAVE",
      "amount": 10,
      "balance": 29,
      "date": "2023-06-15"
    }
  ]
}

Successful money deposit

curl -X POST \
     -H "Content-Type: application/json" \
     -d '{ "amount": 10, "type": "SAVE" }' \
     http://localhost:8080/bank-service/api/v1/accounts/ACCOUNT_001

{
  "result":"SUCCESSFUL",
  "message":"Amount of 10$ successfully deposited in your account",
  "balance":19
}

Successful money withdrawal

curl -X POST \
     -H "Content-Type: application/json" \
     -d '{ "amount": 10, "type": "WITHDRAW" }' \
     http://localhost:8080/bank-service/api/v1/accounts/ACCOUNT_001

{
  "result":"SUCCESSFUL",
  "message":"Amount of 10$ withdrawn from your account",
  "balance":9
}

Insufficient account balance

curl -X POST \
     -H "Content-Type: application/json" \
     -d '{ "amount": 100, "type": "WITHDRAW" }' \
     http://localhost:8080/bank-service/api/v1/accounts/ACCOUNT_001

{
  "result":"FAILED",
  "message":"Insufficient account balance",
  "balance":19
}

TODO

• add the case where the account did not exist
• add exception management
• add logging
• add support for swagger
• add persistence
• add unit tests for the controller
• add BDD test