Bank tech test

This is a small project to practice TDD and OO design.

Specification

Requirements

• You should be able to interact with your code via a REPL like IRB or the JavaScript console. (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 10-01-2012
And a deposit of 2000 on 13-01-2012
And a withdrawal of 500 on 14-01-2012
When she prints her bank statement
Then she would see

date || credit || debit || balance
14/01/2012 ||  || 500.00 || 2500.00
13/01/2012 || 2000.00 ||  || 3000.00
10/01/2012 || 1000.00 ||  || 1000.00

Getting started

Clone this repository to your local machine.

# install dependencies
$ bundle install

# to run tests
$ rspec

To run the program in the irb

$ irb

> require './lib/account'
 => true
> require './lib/transaction'
 => true
> require './lib/printer'
 => true

Approach

I started by writing the user stories and braking the task into smaller steps. I then started to identify what classes and methods I need to implement.

User stories

As a user,
I want to be able to make a bank account.

As an account holder,
I want to be able to make a deposit.

As an account holder,
I want to be able to make a withdrawal.

As an account holder,
I want to see a warning when there are insufficient funds.

As an account holder,
I want to be able to print an account statement.

Classes and methods

The program is split into three classes: Account, Transaction, Printer. Each class is handling a single responsibility.

Account

Account class ties everything together by delegating the functionality of the program to the other classes.

• #deposit() - delegates transaction creation to Transaction class
• #withdraw() - delegates transaction creation to Transaction class
• #statement - delegates statement printing to Printer class

Transaction

Transaction class is responsible for keeping track of all transactions that the account holder makes. It is using class methods to store and retrieve all the transactions.

• .add_to_transactions() - it uses a class variable to store Transaction instances
• .transactions - getter for @@transactions
• .updated_balance() - updates the balance of the account
• sufficient_balance?() - checks if there are sufficient funds to make a withdrawal

Printer

Printer class is responsible for statement creation. Works with Transaction class to format and print the statement.

• #print_statement
• #print_header - private method