@Test
public void shouldAddItemsToList() throws Exception {

    final Debt debt = Debt.debt(thomas, AmountFactory.amount(10), matthias);
    final Add combinationResult = new Add(debt);
    final ArrayList<Debt> list = new ArrayList<>();
    combinationResult.applyTo(list);
    assertThat(list, allOf(
            iterableWithSize(1),
            hasItem(debt)
    ));
}