SE450: JUnit: An example [38/41]

Here is an example set of tests that exercise the getGrade methods of the three strategies from the last homework assignment. These tests do not offer a guarantee that the implementation is correct for every case, but you can see that it covers the differences in the different classes.

package se450.mwright1.hw2;

import junit.framework.*;

/**
 * A sample test case, testing <code>se450.mwright1.hw2.Student</code>.
 *
 */
public class StudentTest extends TestCase {
    
    protected Student student;

    protected void setUp() {
	student = new Student("Test", "Student");
	student.setProject1(50);
	student.setProject2(75);
	student.setProject3(100);
	student.setMidterm(66);
	student.setFinalExam(90);
    }
    
    public StudentTest(String name) {
	super(name);
    }
    
    public static Test suite() {
	return new TestSuite(StudentTest.class);
    }
    
    public void testConstructor() {
	assertTrue(student.getFirst().equals("Test"));
	assertTrue(student.getLast().equals("Student"));
    }
    
    public void testGrade() {
	assertTrue(student.getTotal() == 78);  
	assertTrue(student.getGrade().equals("C"));
    }

    public void testToString() {
	assertTrue(student.toString().equals("[Student: Test Student ]"));

    }
    
}

When writing Unit tests, ask yourself these questions:

• What are the border conditions?
• What type of objects are needed to cover the different possibilities?
• What methods should I not bother testing (only the most trivial getters/setters)
• How would a client of this class expect to use it?
• What kinds of mistakes would a programmer make when using my class?

Write these types of tests. Then, whenever you find a bug, add a test for that bug. Write the test that exposes your bug first. Then, modify your code to make it pass. Then, never get rid of the test and the bug will never reappear.