public void incrementIndex(int task_index) {


        moveTask(task_index, INCREMENT_INDEX);
    }
@Test
    public void shouldIncrementIndexOfGivenTask() {
        Tasks tasks = new Tasks();
        AntTask task1 = antTask("b1", "t1", "w1");
        tasks.add(task1);
        AntTask task2 = antTask("b2", "t2", "w2");
        tasks.add(task2);
        AntTask task3 = antTask("b3", "t3", "w3");
        tasks.add(task3);

        tasks.incrementIndex(0);

        assertThat(tasks.get(0), is(task2));
        assertThat(tasks.get(1), is(task1));
        assertThat(tasks.get(2), is(task3));
    }