Bank tech test

Tech test provided on Week 10 of the Makers Course. Instructions for the projects can be found here. The aim of the project is to produce the best code that I can without a strict time limit.

To run the project

Download

  git clone git@github.com:FayeCarter/bank_tech_test.git
  cd bank_tech_test
  bundle install

Run tests

  rspec

  rubocop

Run program

Run IRB

  irb

Once in IRB

  require './lib/account'
  account = Account.new

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

Process

To get a clearer understanding of the task I created user stories using the requirements and acceptance criteria.

  As a customer,
  So I can save my money,
  I want to be able to deposit money into my account.

  As a customer,
  So that I can access my money,
  I want to be able to withdraw money from my account

  As a customer,
  So that I can manage my account,
  I want to be able to print a statement.

I then created a class diagram to get a clearer understanding the classes that could be used and their interactions

Modelling

User Story 1

• Complete

  As a customer,
  So I can save my money,
  I want to be able to deposit money into my account.

Steps taken:

• Account has initial balance
• Deposit adds to balance
• Deposit increases transaction history
• Deposit is a transaction
  • transactions have date
  • transactions can have credit
  • transactions can have debit
  • transactions can have balance

Approach

I created a repository and installed bundler and RSpec. I updated the Gemfile and the spec_helper to include SimpleCov to help me check my tests coverage. I also added Ruboocop so that I could ensure that my code was properly linted.

My first step was to create and Account class with an initial balance of 0. I initially accessed this by creating a method to display the balance. This was later removed as it became unnecessary.

I created a deposit method that would take a value and increase the account balance. When a deposit is made it is stored in the account transaction history.

I chose to refactor this logic into a transaction method that could handle deposits and withdrawals.

User Story 2

• Complete

  As a customer,
  So that I can access my money,
  I want to be able to withdraw money from my account

Steps taken:

• Withdraw method created that reduces balance
• Withdraw creates a transaction

Approach

As I already had created a transaction class, I updated it to include an option for credit. If a deposit transaction was made, credit would be nil by default. If a withdrawal transaction was made, debit would be nil by default.

User Story 3

• Complete

  As a customer,
  So that I can manage my account,
  I want to be able to print a statement.

Steps taken:

• Create Statement class with a header
• Transactions should be added to account in reverse chronological order
• Statement should take transaction history

Approach

I chose to update deposit and withdraw methods to add transaction to the beginning of the transaction array so the the statement would receive transactions in reverse chronological order.

I initially began to implement the statement to return a string of the statement. when I tested this in irb I noticed that didn't output correctly. I refactored this logic to allow the statement to print the string onto separate lines.