Java Extreme Programming Cookbook

Set Up and Tear Down

Problem

You want to avoid duplicated code when several tests share the same initialization and cleanup code.

Solution

Use the setUp( ) and tearDown( ) methods. Both of these methods are part of the junit.framework.TestCase class.

Discussion

JUnit follows a very specific sequence of events when invoking tests. First, it constructs a new instance of the test case for each test method. Thus, if you have five test methods, JUnit constructs five instances of your test case. For this reason, instance variables cannot be used to share state between test methods. After constructing all of the test case objects, JUnit follows these steps for each test method:

• Calls the test case’s setUp( ) method

• Calls the test method

• Calls the test case’s tearDown( ) method

This process repeats for each of the test methods in the test case. Example 4-3 shows how you can take advantage of setUp( ) and tearDown( ) to avoid duplicated code.

Example 4-3. setUp( ) and tearDown( )

package com.oreilly.javaxp.junit;

import com.oreilly.javaxp.common.BadGameException;
import com.oreilly.javaxp.common.Game;
import com.oreilly.javaxp.common.Ship;
import junit.framework.TestCase;

/**
 * Sample unit tests for the {@link Game} class.
 */
public class TestGame extends TestCase {
    private Game game;
    private Ship fighter;

    public void setUp(  ) throws BadGameException {
        this.game = new Game(  );
        this.fighter = this.game.createFighter("001");
    }

                      public void tearDown(  ) {
        this.game.shutdown(  );
    } public void testCreateFighter( ...