JUnit Tes

[coco24]

Hi, this is my first program using JUnit and I am very lost, this is the piece of code that I am running the test on

public class BoundedBag {

	// Data members
	private int[] contents; // Elements of the BoundedBag.
	private int topPosition; // Index of highest used position in contents.

	/**
	 * Default constructor - creates an empty BoundedBag.
	 */
	public BoundedBag() {
		contents = new int[4];
		topPosition = -1;
	}

	public void add(int theValue) {
		// test if still room

		if (topPosition == 3) {
			// no more room
			return;
		}
		// OK still room
		topPosition++;
		contents[topPosition] = theValue;
	}

	// returns true if theValue is in the BoundedBag
	public boolean contains(int theValue) {
		for (int i = 0; i < topPosition; i++) {
			if (contents[i] == theValue) {
			}
		}
		return true;
	}

	// deletes theValue from the BoundedBag
	// returns true if theValue was in the Bag,
	// otherwise return false.
	public boolean remove(int theValue) {

		// declare i
		for (int i = 0; i < topPosition; i++) {
			if (contents[i] == theValue) {
				// value found move back the other values

				for (int j = i; j < topPosition - 1; j++) {
					contents[j] = contents[j + 1];
				}
				// value found and deleted, return true
				return true;
			}
		}
		// value wasn't found
		return false;
	}
}

Here is the JUnit skeleton

import static java.lang.System.out;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;

import org.junit.Before;
import org.junit.Ignore;
import org.junit.Test;

public class BoundedBagTest {

	// Data Members
	private BoundedBag empty, singleton, typical, full;

	@Before
	public void setup() {
		empty = new BoundedBag();

		singleton = new BoundedBag();
		singleton.add(347);

		typical = new BoundedBag();
		typical.add(33);
		typical.add(33);
		typical.add(-33);

		full = new BoundedBag();
		full.add(1);
		full.add(2);
		full.add(2);
		full.add(-999999999);
	}

	@Test
	public void defaultConstructor() {
		BoundedBag b0 = new BoundedBag();
		out.println("\n*** b0 after default constructor = " + b0);
		assertEquals(0, b0.size());
	}

	@Test
	public void add() {
		out.println("\n***add");
		BoundedBag b1 = new BoundedBag();
		b1.add(1);
		out.println("b1 = " + b1);
		assertEquals(1, b1.size());

		b1.add(2);
		out.println("b1 = " + b1);
		assertEquals(2, b1.size());

		b1.add(2);
		out.println("b1 = " + b1);
		assertEquals(3, b1.size());

		b1.add(-999999999);
		out.println("b1 = " + b1);
		assertEquals(4, b1.size());
	}
}

Can someone help explain how this works please