Simple use of JUnit to test ArrayList : Unit Test « Development Class « Java

Simple use of JUnit to test ArrayList

Simple use of JUnit to test ArrayList
// :
//Simple use of JUnit to test ArrayList
//{Depends: junit.jar}
//From 'Thinking in Java, 3rd ed.' (c) Bruce Eckel 2002
// See copyright notice in CopyRight.txt.

import java.util.*;
import junit.framework.*;

//So we can see the list objects being created,
//and keep track of when they are cleaned up:
class CountedList extends ArrayList {
  private static int counter = 0;

  private int id = counter++;

  public CountedList() {
    System.out.println("CountedList #" + id);

  public int getId() {
    return id;

public class JUnitDemo extends TestCase {
  private CountedList list = new CountedList();

  // You can use the constructor instead of setUp():
  public JUnitDemo(String name) {
    for (int i = 0; i < 3; i++)
      list.add("" + i);

  // Thus, setUp() is optional, but is run right
  // before the test:
  protected void setUp() {
    System.out.println("Set up for " + list.getId());

  // tearDown() is also optional, and is called after
  // each test. setUp() and tearDown() can be either
  // protected or public:
  public void tearDown() {
    System.out.println("Tearing down " + list.getId());

  // All tests have method names beginning with "test":
  public void testInsert() {
    System.out.println("Running testInsert()");
    assertEquals(list.size(), 3);
    list.add(1, "Insert");
    assertEquals(list.size(), 4);
    assertEquals(list.get(1), "Insert");

  public void testReplace() {
    System.out.println("Running testReplace()");
    assertEquals(list.size(), 3);
    list.set(1, "Replace");
    assertEquals(list.size(), 3);
    assertEquals(list.get(1), "Replace");

  // A "helper" method to reduce code duplication. As long
  // as the name doesn't start with "test," it will not
  // be automatically executed by JUnit.
  private void compare(ArrayList lst, String[] strs) {
    Object[] array = lst.toArray();
    assertTrue("Arrays not the same length", array.length == strs.length);
    for (int i = 0; i < array.length; i++)
      assertEquals(strs[i], (String) array[i]);

  public void testOrder() {
    System.out.println("Running testOrder()");
    compare(list, new String[] { "0", "1", "2" });

  public void testRemove() {
    System.out.println("Running testRemove()");
    assertEquals(list.size(), 3);
    assertEquals(list.size(), 2);
    compare(list, new String[] { "0", "2" });

  public void testAddAll() {
    System.out.println("Running testAddAll()");
    list.addAll(Arrays.asList(new Object[] { "An", "African", "Swallow" }));
    assertEquals(list.size(), 6);
        new String[] { "0", "1", "2", "An", "African", "Swallow" });

  public static void main(String[] args) {
    // Invoke JUnit on the class:;
} ///:~

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