jUnit

A quick introduction to Unit Testing with JUnit Cleveland Java Sig March 13, 2002 [email_address]

Extreme Programming The other XP The Planning Game Small Releases Metaphor Simple Design Testing Refactoring Pair Programming Collective Ownership Continuous Integration 40-Hour week On-Site Customer Coding Standards

In XP how you get started Start with a User Story Break the User Story into tasks Estimate and sign up for tasks Find someone to pair with you on a task

The process of Testing First pick a small goal within the task think of how you'll accomplish this goal write the code that will test this goal (several of these may be needed -- write just one)

Example -- Conway's Life Assume... There is infrastructure to run the testing framework. A suite of some sort will keep track of all of the classes containing tests that need to be run. Each of these classes will extend TestCase and will use reflection to run any method named textXXX()

Example -- Conway's Life Start by writing the test code first...

Example -- Conway's Life public void testNewCellIsDead(){ Cell cell = new Cell(); assertTrue(!cell.isAlive()); }

Example -- Conway's Life public void testNewCellIsDead(){ Cell cell = new Cell(); assertTrue(! cell.isAlive() ); } This won't even compile

Next task in Testing first Get the test code to compile. We need Cell class with a Cell() no argument constructor and a isAlive() method that returns a boolean Note how much we know about the code we need just from the test we've written In XP we do the simplest thing that could possibly work

Cell class public class Cell { protected boolean isAlive(){ return true; } }

Test compiles but fails Compile the code (minor success) Run the tests The test fails -- in fact it's often a good idea to make sure that your test fails before it passes so that you know it's actually being called simplest thing might be just to change return to false

Another test public void testLiveCellIsAlive(){ Cell cell = new Cell(); cell. setAlive(true); assertTrue(cell. isAlive() ); }

Need to: add the setAlive() method to Cell so code compiles fix isAlive() method so that both tests pass let's assume you can do this

Clean up test code a little public void testNewCellIsDead(){ Cell cell = new Cell(); assertTrue(!cell.isAlive()); } public void testLiveCellIsAlive(){ Cell cell = new Cell(); cell.setAlive(true); assertTrue(cell.isAlive()); }

Result import junit.framework.TestCase; public class TestCell extends TestCase{ Cell cell; //more...

Result (cont.) public TestCell(String name){ super(name); } protected void setUp() { cell = new Cell(); } //more...

Result public void testNewCellIsDead(){ assertTrue(!cell.isAlive()); } public void testLiveCellIsAlive(){ cell.setAlive(true); assertTrue(cell.isAlive()); } }

The Test Suite import junit.framework.Test; import junit.framework.TestSuite; public class AllTests { public static void main (String[] args) { junit.textui.TestRunner. run (suite()); } //more...

The Test Suite (cont.) public static Test suite ( ) { TestSuite suite= new TestSuite("All JUnit Tests"); suite.addTest( new TestSuite( life.model.TestCell.class ) ); return suite; } }

Running the suite Want tests automated so you can run them all the time Can use from ANT and other tools also Can just run AllTests (it has a main())

Notes JUnit is available at www.junit.org Other languages have other frameworks Challenges in the J2ME world Challenges in distributed world Mock objects and other solutions Issues with acceptance tests

Resources JUnit is available at www.junit.org More resources at www. xprogramming .com Contact me at DSteinberg@core.com

jUnit

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