@Test
void emptyPortfolio() {

    final PortfolioOverview po = new PortfolioOverviewImpl(Collections.emptyMap(), Ratio.ZERO);
    assertSoftly(softly -> {
        softly.assertThat(po.getInvested())
            .isEqualTo(Money.ZERO);
        for (final Rating r : Rating.values()) {
            softly.assertThat(po.getInvested(r))
                .as(r + " invested")
                .isEqualTo(Money.ZERO);
            softly.assertThat(po.getShareOnInvestment(r))
                .as(r + " as a share")
                .isEqualTo(Ratio.ZERO);
        }
    });
}