Junit test method returning statement "void type no allowed"

Question

I have a method in a a Junit test class, which tests if an email has been changed successfully, the problem is that it is returning an error message saying "void type not allowed" and I am not sure why.

Here is the method, which tests if an email has changed successfully but returns the mentioned error.

  @Test
public void testChangeEmail()
{
    assertEquals("001", teacher.getEmail());
    assertEquals("002", teacher.changeEmail("002"));
    assertEquals("002", teacher.getEmail());

}

and here is the whole class,

import static org.junit.Assert.*;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;


public class TeacherTest
{
    private Teacher teacher;

    /**
     * Default constructor for test class TeacherTest
     */
    public TeacherTest()
    {
    }

    /**
     * Sets up the test fixture.
     *
     * Called before every test case method.
     */
    @Before
    public void setUp()
    {
        teacher = new Teacher("Amy Blunt", "001", "MNHA");
    }

    /**
     * Tears down the test fixture.
     *
     * Called after every test case method.
     */
    @After
    public void tearDown()
    {
    }

    @Test
    public void testGetName()
    {
        assertEquals("Amy Blunt", teacher.getName());
    }

    @Test
    public void testMembership()
    {
        assertEquals("001", teacher.getEmail());
    }


    @Test
    public void testQualifications()
    {
        assertEquals("MNHA", teacher.getQualifications());
    }

    @Test
    public void testChangeEmail()
    {
        assertEquals("001", teacher.getEmail());
        assertEquals("002", teacher.changeEmail("002"));
        assertEquals("002", teacher.getEmail());

    }

}

Answer 1

I'm guessing your teacher.changeEmail(); method doesn't actually return anything.

Instead of assertEquals("002", teacher.changeEmail("002")); just call teacher.changeEmail("002");. The next assert checks to make sure the email was properly updated.

@Test
public void testChangeEmail()
{
    assertEquals("001", teacher.getEmail());
    teacher.changeEmail("002")
    assertEquals("002", teacher.getEmail());

}