@Test
void empty() {

    final StrategyProvider r = StrategyProvider.empty();
    assertSoftly(softly -> {
        softly.assertThat(r.getToInvest())
            .isEmpty();
        softly.assertThat(r.getToPurchase())
            .isEmpty();
        softly.assertThat(r.getToSell())
            .isEmpty();
        softly.assertThat(r.getForReservations())
            .isEmpty();
    });
}