University of Sunderland CSE301 Advanced Object-Oriented Software Development Unit 1

Test-Driven DevelopmentTest-Driven Development

CSE301

University of Sunderland

Dr. Giles Oatley

University of Sunderland CSE301 Advanced Object-Oriented Software Development Unit 1

SourcesSources

• Fowler, 2000, Refactoring: Improving the Design of Existing Code, Addison-Wesley.

• http://www.amazon.com/exec/obidos/tg/detail/-/0321109295/103-4060125-0311065

• http://www.amazon.com/exec/obidos/ASIN/0130648841/103-4060125-0311065

• http://www.refactoring.com/catalog/• http://www.win.ua.ac.be/~lore/refactoringProject/index.php

• Extensive discussions on the comp.object newsgroup.

University of Sunderland CSE301 Advanced Object-Oriented Software Development Unit 1

TopicsTopics

• Test-Driven Development

• JUnit

• Refactoring– Principles– Bad Smells in Code– A Catalog of Refactorings

University of Sunderland CSE301 Advanced Object-Oriented Software Development Unit 1

Test-Driven Test-Driven DevelopmentDevelopment

• The test-driven development is the method of software development where tests specify interfaces of implementation and all code must have passed the tests. (Wikipedia)

University of Sunderland CSE301 Advanced Object-Oriented Software Development Unit 1

Test-Driven Test-Driven DevelopmentDevelopment

Roughly:1. Write a test for a bit of functionality.2. Show that it fails.3. Write the code to make the test pass.

Additionally. 1. Do not write production code until there is a failing test.2. Write the simplest possible production code to get the test

to pass.3. Do not write more tests when we have a failing test.4. Do not add to a failing test.

University of Sunderland CSE301 Advanced Object-Oriented Software Development Unit 1

Further CommentsFurther Comments

• If you watched someone doing TDD you would see them oscillating between test code and production code once every minute or so.

• During each oscillation the programmer would add a few lines to his test code, thus making it fail (or not compile) and then add just a few lines to his production code in order to make the test pass (or compile).

• Each oscillation is so simple that it's not worth taking. • Each oscillation is so simple that the risk of error is close to

zero. • If you walk into a room of people working this way, and

chose anyone at random, a minute ago all his code would have been working.

University of Sunderland CSE301 Advanced Object-Oriented Software Development Unit 1

Working with JUnitWorking with JUnit

IMPORTANT TUTORIAL WORK

• Eclipse version (at least) 3.0.• Download and install the examples.• Create a JUnit project. Read the test examples provided for

ideas.• Open the properties for your project. Go to Project

References and select the JUnit project.• Create an AllTests class for your project to run your test

suite.• Create appropriate unit test classes and insert them in your

test suite.

University of Sunderland CSE301 Advanced Object-Oriented Software Development Unit 1

Eclipse and TDDEclipse and TDD

• Work through the Eclipse-JUnit tutorial at: http://www.onjava.com/pub/a/onjava/2004/02/04/juie.html