Question

Our teacher gave us an assignment to write a very simple program in conjunction with his own junit test class. I’ve done that, but I don’t quite understand whether or not i’m getting the right results or if the whole thing is broken.

Here is the class we are testing (the one I wrote):

package person;

public class Person {
    private String name;
    private char sex;

    public Person(String name, char sex) {
        if(name == null || name.equals(""))
            throw new IllegalArgumentException();
        if(sex != 'M' || sex != 'F')
            throw new IllegalArgumentException();

        this.name = name;
        this.sex = sex;
    }

    public void setName(String name) {
        if(name == null || name.equals(""))
            throw new IllegalArgumentException();
        this.name = name;
    }

    public void setSex(char sex) {
        if(sex != 'M' || sex != 'F')
            throw new IllegalArgumentException();
        this.sex = sex;
    }

    public String getName() {
        return name;
    }

    public char getSex() {
        return sex;
    }
}

And here is the JUnit test class:

package parameterchecking;

import person.Person;
import org.junit.Test;
import static org.junit.Assert.*;

/**
 *
 * @author andersb
 */
public class PersonTest2 {

  @Test
  public void constructor() {
    try {
      new Person(null, 'F');
      fail("Should throw exception");
    } catch (IllegalArgumentException ex) { /* expected */ }

    try {
      new Person("", 'F');
      fail("Should throw exception");
    } catch (IllegalArgumentException ex) { /* expected */ }

    try {
      new Person("Anders", 'W');
      fail("Should throw exception");
    } catch (IllegalArgumentException ex) { /* expected */ }
  }

  @Test
  public void setSex() {
    final Person person = new Person("SomeName", 'M');
    try {
      person.setSex('L');
            fail("Should throw exception");
    } catch (IllegalArgumentException ex) { /* expected */ }

    person.setSex('F');
    assertSame('F', person.getSex());
  }

  @Test
  public void setName() {
    final Person person = new Person("Anders", 'M');
    try {
      person.setName(null);
            fail("Should throw exception");
    } catch (IllegalArgumentException ex) { /* expected */ }

    try {
      person.setName("");
            fail("Should throw exception");
    } catch (IllegalArgumentException ex) { /* expected */ }

    person.setName("Henrik");
    assertEquals("Henrik", person.getName());
  }

}

Now, the constructor test passes, but setName and setSex does not. They throw an error “java.lang.IllegalArgumentException”. I don’t see why they won’t pass the test.

JUnit hints that the problem is the “valid” object creation at the start of each test (final Person person), and says that the problem is that I throw an illegal argument exception, which really shouldn’t happen.

Answer 1

if(sex != 'M' || sex != 'F')

should be

if(sex != 'M' && sex != 'F')