public void incrementIndex(int task_index) {


        moveTask(task_index, INCREMENT_INDEX);
    }
@Test
    public void shouldErrorOutWhenTaskIsNotFoundWhileIncrementing() {
        try {
            new Tasks().incrementIndex(1);
            fail("Should have thrown up");
        } catch (Exception e) {
            assertThat(e.getMessage(), is("There is not valid task at position 1."));
        }
    }