How To Destroy a JUnit Test Fixture?

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JUnit Questions and Answers

How To Destroy a JUnit Test Fixture?

In most cases, you don't need to destroy the test fixture used in a test class. The Java garbage collector will destroy all objects used in the test fixture for you automatically.

But if you want to help the garbage collector, you can:

Create an cleanup method with the JUnit "@After" annotation to release all objects used in the test fixture.

Here is an example test class that release the object used in the test fixture with an "@After" method:

import org.junit.*; 
import java.util.*;

// by FYICenter.com
public class GregorianCalendarTest3 {

 // variables for the test fixture
 GregorianCalendar cal = null;

 // initialize the test fixture 
 @Before public void init() {
  cal = new GregorianCalendar();
  cal.set(2008, 12, 31, 23, 59, 59);
 }
 
 // clean up the test fixture
 @After public void cleanup() {
  cal = null;
 }
 
 // testing roll(Calendar.DAY, true) method
 @Test public void nextDayNewYear() {
  cal.roll(Calendar.DAY_OF_MONTH, true);
  Assert.assertEquals("Next day of 31-Dec-2008 is year 2009", 
     2009, cal.get(Calendar.YEAR));
  }

 // testing roll(Calendar.DAY, true) method
 @Test public void nextDayNewMonth() {
  // testing starts
  cal.roll(Calendar.DAY_OF_MONTH, true);
  Assert.assertEquals("Next day of 31-Dec-2008 is January", 
     0, cal.get(Calendar.MONTH));
  }
}

JUnit test runner will automatically run the "@After" method after calling each "@Test" method. In our example, the test runner will those methods in this order:

 @Before public void init()
 @Test public void nextDayNewYear()
 @After public void cleanup()

 @Before public void init()
 @Test public void nextDayNewMonth()
 @After public void cleanup()

Well, the "@After" method is really unnecessary. But if there are external resources created in the test fixture, you must release those resources yourself. See the next question.

(Continued on next question...)