Bank Technical Test in Javascript

Overview

Solo project to solve a technical challenge with a focus on clean well crafted code. Program allows user to manage finances through a simple command line interface.

Personal Objectives:

• To approach planning meticulously
• To write DRY, readable, clean code from scratch that is easy to update and manage.
• High test coverage (>95%)
• To learn how to use a new testing framework (Jest)

Setup

$ git clone git@github.com:fwill22/bank-tech-test-JS.git
$ cd bank-tech-test-JS
$ yarn install
$ node

How to use

In REPL:

> let connection = require('./src/account')
> let account = new connection
> account.deposit(1000.75)
> account.withdraw(800)
> account.balance()
> account.viewStatement()

Testing and Linting

Run Tests

yarn test

Jest Results

Run Linting

yarn lint

Planning and Approach:

User Stories

As a user
So I can be part of a cashless economy
I want to be able to open an empty bank account, with a starting balance of £0.

As a user
So I can store my money securely
I want to be able to deposit it into my account

As a user
So I can buy things untracked 
I want to be able to withdraw money from my account

As a user
So I can have emergency funds
I would like to have an overdraft limit

As a user
So I can check how much money I have saved
I want to be able to see my current account balance and transaction history on a printed statement.

As a user
So I can keep on top of my money habits
I want my account statement to display the date, transaction amount, type, and updated balance.

As a user
So I can see an up to date history of my transactions
I want to be able to see my account statement listed in reverse chronology by date created

Edge cases:

As a user
So I can stay in the black
I want my account to prevent withdrawal if I have insufficient funds

As a bank manager
So I can ensure the efficient operation of my business
I want to be able to notify customers if they are depositing or withdrawing amounts ≤ £0. 

As a user
So I know I am adding real money
I want to be notified if I try to enter anything other than an integer or float

Domain Model

Class	Account
Properties	opening_balance, overdraft limit, transaction history, statement_class, transaction_class
Actions	deposit, withdrawal, balance, sufficient_funds?, print_statement, save_transaction

Class	Transaction
Properties	Date, Type, Amount, Current Balance
Actions	constructor

Class	Statement
Properties
Actions	format(date), format(amount), format(transaction), format(header), format(statement), print(transaction_history)

CRC Cards

CRC Cards

Account:

Responsibilities:	Collaborators:
Knows about:	Transaction, Statement

Planning Notes & Ideas:

[Draft]

• withdrawal [- if sufficient_funds?] - add to transaction_history (private method)
  
• balance (iterates through transaction history) and
  
• @transaction_history = []

Reflections [Notes on changes/adaptations to design/models]

Feedback

> Positive
> To improve [ ]

Dependencies

• JavaScript
• Node
• Jest
• ESLint
• Husky

Requirements

You should be able to interact with your code via the JavaScript console. 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 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  |

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Ruby Version

I have also written this project in Ruby - you can find the repo here.