Test.java

class State {
    public static boolean someState;
}

class GoodTest {

    @Test
    public void checkState() {
        assertFalse(State.someState);
    }
}

class RogueTest {
    
    @Test
    public void playWithState() {
        State.someState = true;
        // Test something that relies on State#someState
        // Whoops! We forgot to reset State#someState to its original value!
    }
}