An introduction to Test Driven development in Java

1. Java 201 – Intro to Test-Driven
Development in Java

2. Agenda
• TDD Overview
• Test Frameworks
• Setting Up your IDE
• Writing your first Unit Test
• Anatomy of a Unit Test
• Hands-on Exercise

3. Intro to Test-Driven Development
in Java
TDD Overview

4. TDD Overview
• What is TDD
• Why TDD
• Feedback Loop
• TDD Workflow

5. What is TDD?
• Technique for specifying system features with
tests
• Tests are written before production code
• Simple, repeated, short-cycled mechanism
• Automated mechanism for regression testing
of code changes

6. Why TDD?
• Improves code quality
• Minimises defects
• Increases code maintainability
• Reduces the cost of change
• Provides a quick feedback
• Acts as documentation for your code
• Reduces fear of breaking things
• It is fun and infectious 

7. Feedback Loop

8. PDCA Explained
• PLAN
– Establish the objectives
– Identify steps required to meet the objective
• DO
– Execute the steps to meet the objective
• CHECK
– Study actual results and compare against expected results
– Look for completeness in meeting the objectives
• ACT
– If CHECK step shows objectives met vs. with the plan,
repeat with next objective else rework and CHECK again

9. TDD Workflow

10. Intro to Test-Driven Development
in Java
Test Frameworks

11. What is a Test Framework?
• An abstract set of…
– concepts, processes, procedures, environments
• Where automated tests are…
– designed, implemented and executed
• Includes physical structures for…
– test creation
– test execution
• As well as…
– logical interactions amongst components

12. Why Test Frameworks?
• Provides the basis of test automation
• Simplifies test automation efforts
• Provides concepts and tools that support
automated testing

13. Common Test Frameworks
• Code Testing
– Junit (http://www.junit.org)
– TestNG (http://testng.org)
• UI Testing
– Selenium (www.selenium.org)
– Appium (http://appium.io/)
• API Testing
– SoapUI (http://www.soapui.org)
– RestAssured (https://code.google.com/p/rest-assured)

14. Intro to Test-Driven Development
in Java
Setting Up your IDE

15. Setting Up
• Required Software
• Download JUnit
• Create Java201 Project
• Add JUnit to the Classpath
• Create HelloGreetingTest
• Run the HelloGreetingTest
• Create the HelloGreeting class
• Re-run the HelloGreetingTest

16. Required Software
• IDE
• Java SDK
– http://www.oracle.com/technetwork/java/javase/
downloads/jdk8-downloads-2133151.html
• JUnit
– www.junit.org

17. Download JUnit
• Download the following files from
www.junit.org to a folder on your hard drive
– junit.jar
– hamcrest-core.jar

18. Create Java201 Project
• Create new project named Java201
• Create a new source folder named test in the
java201 project
• Create a lib folder in the Java201 project
• In the test source folder, create the
java201.greetings package

19. Add JUnit to the Classpath
• Copy the junit.jar and hamcrest-core.jar files to
the lib folder of your project
• Refresh the project to import the new contents
of the lib folder
• In Eclipse, click on the Java201 project, select
File>Properties>Build Path and click on
Libraries tab
• Click Add JARs, browse to the project lib folder,
select both jar files and click OK twice

20. Create HelloGreetingTest.java
• In Eclipse, Right-click the test folder, select New>JUnit Test Case,
enter HelloGreetingTest in the Name field and click Finish

21. HelloGreetingTest.java

22. Implement HelloGreetingTest.java

23. Run the HelloGreetingTest
• In Eclipse, Right-click the HelloGreetingTest and select
Run As>JUnit Test

24. Create HelloGreeting class
• In Eclipse, right-click the src folder and select New>Class, enter
HelloGreeting as class name and click Finish
• Create a sayHello() method that returns the String “Hello, TDD!”

25. Re-run the HelloGreetingTest
• Declare and initialise HelloGreeting object and
assert it returns “Hello, TDD!” and rerun the test

27. Intro to Test-Driven Development
in Java
Anatomy of a Unit Test

28. Anatomy of a Unit Test
Declaration of
class under test
setUp() runs once
before each test method
A test method
Initialization of
class under test
tearDown() runs once
after each test method
Checking test results

29. Intro to Test-Driven Development
in Java
Hands-on Exercise

30. Exercise: Game of Cards
• Using TDD, create the following building blocks of a
typical card game
– Card
• Has a suite (Club, Heart, Diamond, Spade) and rank (2-10, Jack,
Queen, King, Ace)
• Ace is highest card
– Hand
• Consists of one or more Cards
– Deck
• Contains 52 Cards, 13 cards per suite
– Dealer
• Deals cards from a deck
• Each player will be dealt a Hand of Cards

31. Card
rank
suite
getRank() : Rank
setRank() : void
getSuite() : Suite
setSuite() : void
Hand
cards
maxCards
getNoOfCards() : int
drawCard(): Card
addCard() : void
Deck
cards
getCards(int noOFCards) :
List<Card>
Dealer
deck
deal(noOfCards) : Hand
Game of Cards Domain Model

32. Solution: Game of Cards
https://github.com/hawkmanacademy/java201

33. Resources
• UML Distilled - http://amzn.to/1BBHcXi
• Test Driven Development –
http://amzn.to/1xqPllN
• XUnit Patterns - http://xunitpatterns.com/
• Junit – www.junit.org