Using jUnit

This is a simple intro to using the JUnit framework. For more information on jUnit and why it's swell, for more advanced examples, or to download jUnit, go to www.junit.org. (I'm not involved in the jUnit development effort; I'm just an end user).

Download the junit framework from www.junit.org
Unpack the junit distribution and add the file "junit.jar" to your classpath.
Write your test case
```
import junit.framework.TestCase;
 
public class tests extends TestCase
{
 
 public tests(String s)
 {
  super(s);
 }
 
 public void testA()
 {
  assertTrue(true);
 }
 public void testB()
 {
  assertTrue(false);
 }
 

 public void setUp()
 {
  System.out.println("setUp");
 }
 
 public void tearDown()
 {
  System.out.println("tearDown");
 }
 
}
```
This is a minimalistic implementation of a test. Notice a few things about this class.
1. It implements the junit.framework.TestCase class.
2. It provides a constructor that takes a string as its argument.
3. It contains a bunch of methods called "test...". These are the test cases.
4. It implements methods called setUp() and tearDown(). These methods are called before and after each test case, and provide convenient places to initialize and free resources.
5. Within the test cases, it uses assertTrue(). This method throws an exception if its argument evaluates to false. There are several other assertions provided by the framework, by the junit.framework.Assert class (an ancestor of the TestCase class). In the class above, testA() will pass and testB() will fail.
run the test case. There are two ways to run it:
1. java junit.textui.TestRunner tests -- run the test, generating text output
2. java junit.ui.TestRunner tests -- run the test in a GUI tool