A talk at the Graduate Developer community on test driven development. Helping students and graduates understand the point of a test first approach, demonstrate the tools and show how easy it is to start.

1. Open Source Jumpstart:
Improve your development
Skills
©LeanAgileMachine
Creative Commons License

2. Graduate Developer
Community
Meet with Companies
www.grad-dc.co.uk looking for interns
Talk to experienced
blog.grad-dc.co.uk developers & testers
Ask questions about
what you learnt
tonight
©LeanAgileMachine
Creative Commons License Socialse

3. Goals of OS Jumpstart
● What tools are out there
● What should you know
● Show how Unit Testing tools support the agile
process
©LeanAgileMachine
Creative Commons License

4. Goals of this session
● Understand the value of TDD
● Give you confidence to start learning TDD
● Tools to use to start learning
● I cant teach you TDD in one evening, sorry!
● TDD is as big as learning something like OO
● A bit of practical experience
● Pair up and try it out
● Deliberate practice
©LeanAgileMachine
Creative Commons License

5. Have you tried ”Test First” ?
Raise your hand if you already tried TDD and
”test first” development ?
©LeanAgileMachine
Creative Commons License

6. Where does TDD fit
©LeanAgileMachine
Creative Commons License

7. So what is TDD ??
©LeanAgileMachine
Creative Commons License

8. A design activity
● What is the challenge (the requirements)
● What are the concepts we are dealing with
● What is valuable
● What behaviour do I need to understand
● How do I know I have met the challenge
● How do I know I can change
©LeanAgileMachine
Creative Commons License

9. Understanding the problem
● Behaviour
● Concepts
● Stakeholders
● Values
● Priorities
©LeanAgileMachine
Creative Commons License

10. The TDD cycle
● Write a failing test so
we know it tests
something
● Write code to make
the test pass
● Refactor code to be
as simple as possible
©LeanAgileMachine
Creative Commons License

11. Continuous / Fast Feedback
● Are we there yet ?
● Your own ”mini-me” tester as a guide
● Only scratching the surface of testing though
©LeanAgileMachine
Creative Commons License

12. What tools are involved
Jenkins CI
©LeanAgileMachine
Creative Commons License

13. Anatomy of a test
©LeanAgileMachine
Creative Commons License

14. Make the test compile
©LeanAgileMachine
Creative Commons License

15. Write a class
©LeanAgileMachine
Creative Commons License

16. Common assertions
● assertEquals()
● Two objects of the same type are equal in value
● assertNotNull()
● The object does not have a null value
● assertTrue()
● The statement results is a true evaluation
● assertSame()
● Two objects are the same
http://junit.sourceforge.net/javadoc/org/junit/Assert.html
©LeanAgileMachine
Creative Commons License

17. JUnit Annotations
● @Test
● @Ignore
● Defines a method as a test
● Dont run this
● @Test(expected=exception.class) test – use
● Fails if a specific exception is no sparingly
thrown
● @Test(timeout = 1000)
● Fails if test takes too long
(milliseconds)
http://junit.sourceforge.net/javadoc/org/junit/Test.html
©LeanAgileMachine
Creative Commons License

18. Test ”smells”
● Testing code rather
than behaviour ● Multiple assertions
● Too specific per method
● Changing tests every ● Bloated tests
time you refactor ● Harder to refactor
● Addressing to many
scenarios
● Harder to understand
and maintain
©LeanAgileMachine
Creative Commons License

19. A bad test example
@Test
public void equalsCheck() {
System.out.println("* VectorsJUnit4Test: equalsCheck()");
assertTrue(Vectors.equal(new int[] {}, new int[] {}));
assertTrue(Vectors.equal(new int[] {0}, new int[] {0}));
assertTrue(Vectors.equal(new int[] {0, 0}, new int[] {0, 0}));
assertTrue(Vectors.equal(new int[] {0, 0, 0}, new int[] {0, 0, 0}));
assertTrue(Vectors.equal(new int[] {5, 6, 7}, new int[] {5, 6, 7}));
assertFalse(Vectors.equal(new int[] {}, new int[] {0}));
assertFalse(Vectors.equal(new int[] {0}, new int[] {0, 0}));
assertFalse(Vectors.equal(new int[] {0, 0}, new int[] {0, 0, 0}));
assertFalse(Vectors.equal(new int[] {0, 0, 0}, new int[] {0, 0}));
assertFalse(Vectors.equal(new int[] {0, 0}, new int[] {0}));
assertFalse(Vectors.equal(new int[] {0}, new int[] {}));
assertFalse(Vectors.equal(new int[] {0, 0, 0}, new int[] {0, 0, 1}));
assertFalse(Vectors.equal(new int[] {0, 0, 0}, new int[] {0, 1, 0}));
assertFalse(Vectors.equal(new int[] {0, 0, 0}, new int[] {1, 0, 0}));
assertFalse(Vectors.equal(new int[] {0, 0, 1}, new int[] {0, 0, 3}));
}
©LeanAgileMachine
Creative Commons License

20. Quick Netbeans / JUnit demo
- create a new project
- create your first test
- run the JUnit testrunner
- write code to fix the test
- run the JUnit testrunner
- write another test...
©LeanAgileMachine
Creative Commons License

21. Your turn
- pair up
- fire up netbeans
- start a new Java Application project
- or check out my project
- read the basic requirements
- write a test...
©LeanAgileMachine
Creative Commons License

22. Deliberate practice
● Goal is to practice TDD
● Become comfortable with the tools
● Gain experience in writing tests
● Improve confidence in TDD
● The resulting code algorithms are not important
● I dont care how fast your calculator calculates
● You're here to learn not to produce
©LeanAgileMachine
Creative Commons License

23. Hamcrest asserts
● Hamcrest is a pattern matching library
● Can help make you test logic more human readable
AssertThat() - instead of JUnit asserts
assertThat(myCalc.addTwoNumbers(6, 7),
is(6 + 7));
assertThat(myCalc.addTwoNumbers(6, 7),
is(not(6 + 9)));
©LeanAgileMachine
Creative Commons License

24. Build Tools
● Build Automation
● Compile, test and deploy code
from your repository
Ant.apache.org
ant.apache.org/ivy
Maven.apache.org
Comparison of tools:
http://ant.apache.org/ivy/
m2comparison.html
©LeanAgileMachine
Creative Commons License

25. Integrated Development
Environments
● Manage large / multiple projects
● Debugger
● Autocompletion (code api completion)
● Refactoring .org
● Build management
Ant / Maven – compile, test, deploy
.org
●
● Integration
● Application servers, databases, unit testing,
Scm, bug tracker, CI server, IntelliJ IDEA
jetbrains.org
©LeanAgileMachine
Creative Commons License

26. Keep the build bunny happy
● Tests help prevent
build errors
● You can run your
tests before you
anger the build
bunny
©LeanAgileMachine
Creative Commons License

27. Collaborative workspace
● Can show progress of your
tests
Confluence
● Show you which tests are
failing
● Gives everyone a sence of
progress
©LeanAgileMachine
Creative Commons License

28. Summary
● TDD is a design activity
● Gives you time to use your brain before coding
● This session was just enough to get you going
● Try doing some coding kata
● Try a coding dojo or code retreat
● LJC / GDC organising these soon !
● Monthly Python, Clojure, Scala dojos aready
running
©LeanAgileMachine
Creative Commons License

29. We want your feedback
©LeanAgileMachine
Creative Commons License

30. Graduate Developer
Community
www.grad-dc.co.uk
Meet with Companies
blog.grad-dc.co.uk looking for interns
Talk to experienced
developers & testers
Ask questions about
what you learnt
tonight
Socialse
©LeanAgileMachine
Creative Commons License

31. TDD / BDD Workshop
●
Half day workshop at SkillsMatter 17 th May
● Part of London Tester Gathering days
http://bit.ly/LTGDays2011
©LeanAgileMachine
Creative Commons License

32. Thank you
Useful links
John@jr0cket.com
John.Jr0cket.co.uk
Toolingup.Jr0cket.co.uk
Ubuntu.Jr0cket.co.uk
Growing OO Software,
www.grad-dc.co.uk guided by tests
blog.grad-dc.co.uk
©LeanAgileMachine
Creative Commons License