Bank Tech Test

This is a submission for a practice tech test at the Makers Academy.

Specifications

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

Approaching the problem

User stories

From the specifications above I prepared the following user stories:

As a Customer,
So that I can keep my money safe
I would like to be able to deposit cash in Bank

As a Customer 
So that I can get access to the money I deposited
I would like to withdraw the cash from the Bank

As a Customer
So that I can see what is happening with my money
I would like to print out a statement of transactions

As a Customer
So that I can see how much money I have left
I would like my statement to show balance after each transaction

As a Customer
So that I can see what transaction took place when
I would like my statement to show the date of each transaction

As a Customer
So that I can see the context of my transactions
I would like my statement to show latest entries first

Domain Object Model

From the User Stories above, I created the following DOM table:

Object	Message
User
Bank	.deposit(amount)
	.withdraw(amount)
	.statement

Diagramming the Structure

Drawing on my understanding of the OOP practices, I have created the following diagram for my program:

Getting Started

Instructions

To play around with this implementation, do the following:

1. Fork and clone the repo
2. cd into the directory where you placed the cloned repo
3. Run bundle install
4. Fire up your favourite REPL (I prefer PRY, but IRB would do).
5. Then:

• type require './lib/bank.rb' (this will load up the bank.rb file (main application file) into the REPL)

• create new bank like so bank = Bank.new

• now you can:

  • deposit funds like so bank.deposit(amount) where the amount can be any positive number greater than 0 (0 or negative numbers will throw an error)
  • withdraw funds like so bank.withdraw(amount) where the amount can be any positive number greater than 0 (0 or negative numbers will throw an error)
  • obtain a statement like so bank.statement

Demo

[1] pry(main)> require './lib/bank.rb'
[2] pry(main)> bank = Bank.new
[3] pry(main)> bank.deposit(1000)
[4] pry(main)> bank.deposit(2000)
[5] pry(main)> bank.withdraw(500)
[6] pry(main)> bank.statement
date || credit || debit || balance
19/06/2018 ||  || 500.00 || 2500.00
19/06/2018 || 2000.00 ||  || 3000.00
19/06/2018 || 1000.00 ||  || 1000.00
[7] pry(main)>

Running the tests

I used RSpec for testing and Simplecov for coverage analysis.

The testing can be done by running rspec in the command line

The output should be:

16 examples, 0 failures, 16 passed

COVERAGE: 100.00% -- 105/105 lines in 6 files

Break down of tests

The tests breakdown is as follows

Bank
  #deposit
    should take an amount to be deposited
    should throw an error if the #deposit amount is less than 0
    should throw an error if the #deposit amount is 0
    should credit the Ledger Class
  #withdraw
    should take an amount to be withdrawn
    should credit the Ledger Class
    should raise an error if the #withdraw amount is less than 0
    should check with Ledger Class that the withdrawal does not exceed the available
 balance
    should raise error if the #withdrawal amount exceeds the available balance
  #statement
    should call the StatementPrinter Class and provide a ledger

Ledger
  #debit
    should respond to the #debit method
    should push amount and transaction timestamp into @transactions record array
  #credit
    should respond to the #credit method
    should push amount and transaction timestamp into @transactions record array

StatementPrinter
  #print_statement
    should respond to #print_statement with 1 argument
    should print the statement to the screen with a heading

Coding Style Tests

Rubocop is used to monitor code style (which detects one offence at the moment - a line being too long on the statement printer.)

Inspecting 4 files
...C

Offenses:

lib/statement_printer.rb:6:81: C: Metrics/LineLength: Line is too long. [170/80]

4 files inspected, 1 offense detected

Possible Improvements

• Nice looking command-line interface menu (old ATM-style)
• Allow users to select which period they would like to print a statement for
• Adding withdrawal charges, interest accrual, etc.

Authors

• Igor Ryabchuk

Acknowledgments

• Makers Academy for making me love coding more than I thought I could.