Answer 5: Assertion Messages

import junit.framework.TestCase;
import org.apache.commons.lang.math.*;

public class FractionTest extends TestCase {
    
    private Fraction half;
    private Fraction fourth;

    protected void setUp() {
        half = Fraction.getFraction(2, 4);
        fourth = Fraction.getFraction(1, 4);       
    }
    
    public void testAddition() {
        Fraction actual = half.add(fourth);
        Fraction expected = Fraction.getFraction(3, 4);
        assertEquals("Could not add 1/2 to 1/4", expected, actual);
    }
    
    public void testSubtraction() {
        Fraction actual = half.subtract(fourth);
        Fraction expected = fourth;
        assertEquals("Could not subtract 1/4 from 1/2",expected, actual);
    }
    
    public void testAddNumberToItself() {
        Fraction actual = half.add(half);
        Fraction expected = Fraction.ONE;
        assertEquals("Could not add 1/2 to itself using same object",
                      expected, actual);
    }
    
}