Junit Testing with an Array List

Question

I have a method set up to add users to an ArrayList, and return false if the same user is added:

public boolean addUser(K pass, V user)
{
    if (username.contains(user))
    {
        return false;
    }
    else
    {
        password.add(pass);
        username.add(user);
        size++;
        return true;
    }
}

Then I have a JUnit test to assertFalse(true) because that's what my method returns when adding two users with the same name:

@Test
public void testAddingTwoOfTheSameUserToArrayList() {
    User<String, String> user1 = new User<String, String>();
    user1.addUser("password", "SpeedinDave");
    user1.addUser("password", "SpeedinDave");
    assertFalse(true);
}

However, it the test always turns up false (red bar). Any ideas?

What do you expect assertFalse(true) to do? And why are you never using the results of addUser? — Jon Skeet
– Jon Skeet, Commented Jun 4, 2013 at 15:46
you are wanting to assert the return value, so you need to capture the return value and pass that as the argument to assertFalse() — Kevin Welker
– Kevin Welker, Commented Jun 4, 2013 at 15:47
First, what @Quetzalcoatl said. Second, if you do use assertFalse you should put in false NOT true. — AnthonyW
– AnthonyW, Commented Jun 4, 2013 at 16:02

eternay · Accepted Answer · 2013-06-04 15:46:33Z

8

You should test something like that:

@Test
    public void testAddingTwoOfTheSameUserToArrayList() {
        User<String, String> user1 = new User<String, String>();
        user1.addUser("password", "SpeedinDave");
        assertFalse(user1.addUser("password", "SpeedinDave"););
    }

to be sure that the second addUser() returns false.

assertFalse(b) will succeed if the parameter b is false. So if you pass true, it will always fail.

answered Jun 4, 2013 at 15:46

eternay

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1 Comment

Kevin Meredith Over a year ago

It might also be worthwhile to modify the first user1.addUser("password", "SpeedinDave"); to be assertTrue(user1.addUser("password", "SpeedinDave"));

Mark · Accepted Answer · 2013-06-04 15:57:56Z

3

Right now you are not testing the return value of your addUser() method, but rather that the boolean constant true evaluates to false (this will never be true). You probably want something like:

@Test
    public void testAddingTwoOfTheSameUserToArrayList() {
        User<String, String> user1 = new User<String, String>();
        assertTrue(user1.addUser("password", "SpeedinDave"));
        assertFalse(user1.addUser("password", "SpeedinDave"));
    }

answered Jun 4, 2013 at 15:57

Mark

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