@Test
public void shouldReturnParticipantsOfExpense() throws Exception {

    final Expense expense = anExpense()
            .withDebtee(thomas)
            .withShares(
                    randomShare(thomas),
                    randomShare(david),
                    randomShare(lukas)
            )
            .build();
    final Set<Person> participants = expense.getParticipants();
    assertThat(participants, containsInAnyOrder(thomas, david, lukas));
}