Test Driven Discovery - Java Date Durations

import junit.framework.TestCase;
import java.util.Calendar;
import java.text.DateFormat;
 
// Eclipse/WebSphere has the required jar file and it is
// available from http://junit.org
// Run the tests from Command Prompt: 
// java -classpath .;junit.jar CalcTimeTest.java
// or “Run As JUnit Test” in Eclipse/WebSphere 

public class CalcTimeTest extends TestCase {

   /*
    *   test Calendar.setTimeInMillis()
    */
   public void testOneDayByMillis() {
      long now = System.currentTimeMillis();

      Calendar today = Calendar.getInstance();
      today.setTimeInMillis( now ); 

      Calendar tomorrow = Calendar.getInstance();
      tomorrow.setTimeInMillis( now + 1000 * 60 * 60 * 24 );

      Calendar difference = Calendar.getInstance();

      difference.setTimeInMillis( tomorrow.getTimeInMillis() - 
                                  today.getTimeInMillis() ); 

      assertEquals( difference.getTimeInMillis(),  1000 * 60 * 60 * 24 );
   } 

   /*
    *   test Calendar.roll()
    */

   public void testRollOneDay() {
      long now = System.currentTimeMillis();
 
      Calendar today = Calendar.getInstance();
      today.setTimeInMillis( now );

      Calendar tomorrow = Calendar.getInstance();
      tomorrow.setTimeInMillis( now );
      tomorrow.roll( Calendar.DATE, true );     

      Calendar difference = Calendar.getInstance();

      difference.setTimeInMillis( tomorrow.getTimeInMillis() - 
                                  today.getTimeInMillis() );
 
      assertEquals( difference.getTimeInMillis(), 1000 * 60 * 60 * 24  );
   }

   /*
    *   test Calendar.add()
    */
   public void testAddDay() {

      long now = System.currentTimeMillis();

      Calendar today = Calendar.getInstance();
      today.setTimeInMillis( now ); 

      Calendar tomorrow = Calendar.getInstance();

      tomorrow.setTimeInMillis( now );
      tomorrow.add( Calendar.DATE, 1 );

      Calendar difference = Calendar.getInstance();
      difference.setTimeInMillis( tomorrow.getTimeInMillis() - 
                                  today.getTimeInMillis() );
      assertEquals( difference.getTimeInMillis(), 1000 * 60 * 60 * 24  );

   }           

   /*
    *   test Calendar is lenient with invalid dates
    */
   public void testSetYYYYMMDD() { 

      Calendar today = Calendar.getInstance();
      today.set( 2008, 01, 32 );

      Calendar tomorrow = Calendar.getInstance();
      tomorrow.set( 2008, 01, 33 );

      Calendar difference = Calendar.getInstance();

      difference.setTimeInMillis( tomorrow.getTimeInMillis() - 
                                  today.getTimeInMillis() );

      assertEquals( difference.getTimeInMillis(),  1000 * 60 * 60 * 24  );

   }

   /*
    *   test Calendar is lenient with invalid dates
    */
   public void testYYYYMMDDFormat() {
      Calendar today = Calendar.getInstance();
      today.set( 2008, 01, 32 );  // Remember: month Zero is January
      DateFormat prettyPrint = DateFormat.getDateInstance();

      assertEquals( prettyPrint.format( today.getTime() ), "Mar 3, 2008");
   }

   public static void main(String[] args) {
      junit.swingui.TestRunner.run(CalcTimeTest.class);  // OLD SCHOOL! 
   }
}