• Create domain models from user stories
• Create class diagrams from domain models
• Use a red, green, refactor approach to develop robust software
• Use object-oriented principles to organise a codebase

• Fork this repository and clone the forked version to your machine
• Open the root directory of the project in IntelliJ

It's time to flex your programming skills. There are no classes or tests included in this repository to get you started, but you will find the usual ../java/com/booleanuk/core directories to place your classes and tests in.

Your task is to use everything you've learned to build a small banking application.

1. You must create domain models from the user stories provided and include them in the repository
2. You must create class diagrams from your domain models
3. You must use a test-driven development approach to complete this challenge, demonstrate this by committing your work after writing a test and after writing source code to pass it
4. You must demonstrate object-oriented principles. You need not include every concept, but you should strive to include as many as possible
5. You can decide whether to use composition, inheritance, or a combination of both, but at least one must be present

As a customer,
So I can safely store and use my money,
I want to create a current account.

As a customer,
So I can save for a rainy day,
I want to create a savings account.

As a customer,
So I can keep a record of my finances,
I want to generate bank statements with transaction dates, amounts, and balance at the time of transaction.

As a customer,
So I can use my account,
I want to deposit and withdraw funds.

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

As an engineer,
So I don't need to keep track of state,
I want account balances to be calculated based on transaction history instead of stored in memory.

As a bank manager,
So I can expand,
I want accounts to be associated with specific branches.

As a customer,
So I have an emergency fund,
I want to be able to request an overdraft on my account.

As a bank manager,
So I can safeguard our funds,
I want to approve or reject overdraft requests.

As a customer,
So I can stay up to date,
I want statements to be sent as messages to my phone.

When you run a test, it's either going to pass or fail. When it fails, you'll be presented with a big red stream of text. This is called a stack trace and, though intimidating, does contain some useful information.

One of the core skills of a developer is debugging stack traces like this. The stack trace details in which classes & files the failure happened, and gives you a line number at the end. Most of the lines in the stack trace are irrelevant most of the time, you want to try and identify the files that you're actually working with.

In the sample screenshot below, we've tried to complete the first step of the exercise but provided an invalid value. Then we run the test associated with it, and we see a big red stack trace, a test failure.

At the top, we see expected: <32> but was: <33>. This means the test expected the value to be 32, but the value the student provided was 33. We can see this in the code snippets at the top of the screenshot.

In the stack trace itself, we see this line: at app//com.booleanuk.core.ExerciseTest.shouldBeAged32(ExerciseTest.java:20). This is helpful! This tells us the exact line in the ExerciseTest.java file (line 20) where the failure happened, as well as the method name (shouldBeAged32), helping us to identify where the issue began. This is the kind of thing you need to look for; a relevant file name, method name, class name and line number to give you a good starting point for debugging.