Bank Tech Test

Specification:

Requirements

• You should be able to interact with your code via a REPL like IRB or Node. (You don't need to implement a command line interface that takes input from STDIN.)
• Deposits, withdrawal.
• Account statement (date, amount, balance) printing.
• Data can be kept in memory (it doesn't need to be stored to a database or anything).

Acceptance criteria

**Given** a client makes a deposit of 1000 on 10-01-2023  
**And** a deposit of 2000 on 13-01-2023  
**And** a withdrawal of 500 on 14-01-2023  
**When** she prints her bank statement  
**Then** she would see:

date || credit || debit || balance
14/01/2023 || || 500.00 || 2500.00
13/01/2023 || 2000.00 || || 3000.00
10/01/2023 || 1000.00 || || 1000.00

My approach

Designing and planning

Using the acceptance criterea and product specification I began planning the architecture of my program, starting with a top-down overview of the classes and methods that I wanted and how they would interact.

I then created application and UML diagrams to help me visualise how it may look:

This allowed me to make any adjustments before outlining the class system in a design file.

Code Structure

I wanted my program to closely follow the single responsiblity principle, with classses and methods that are decoupled, flexible and scalable. This meant splitting my app into 4 classes:

1. Account - this would manage how a user interacts with the bank account
2. Validator - this would validate any transactions a user makes
3. LogTransaction - this would log a users transaction history
4. PrintStatement - this would handle formatting and printing bank statements

Program example:

In the below example, a user is running the program in Node. When they program is initialised, the balance is set to 0 and a new instance of the LogTransaction class is created to track the user's transactions.

 const Account = require('./Account');
 const myAccount = new Account();
 
 const depositTransaction = {
  date: "2022-01-23",
  debit: 500,
  credit: 0
}

const withdrawTransaction = {
  date: "2022-01-24",
  debit: 0,
  credit: 250
}

myAccount.deposit(depositTransaction);
myAccount.withdraw(withdrawTransaction);

console.log(myAccount.printStatement());

They make a single deposit and a single withdraw. When each of these transactions is called, the add method is called and the transaction is formatted and stored in the log.

When the user calls the printStatement method, a new instance of the printStatement class is created, and the following statment is printed to the console:

date || credit || debit || balance
2022-01-24 ||  || 250.00 || 250.00
2022-01-23 ||  ||  || 500.00

How to use

1. Clone this repository
2. Install dependencies with npm install
3. Run tests with npx jest

Tests

The programme contains two kinds of tests:

• Unit tests for each class, divided into test blocks for each method
• An integration test

Extending the program

If I was extending the programme, I would add the following functionality:

• Currency handling: present statements in a currency format (could be GBP or a setting a user could input)
• Add user interactivity:
  • Allow user to create and access account
  • encrpyt and store account information
  • connect to an account database
• Add a user interface