start = IntraDayDate.create(today, hours(3));
assertThat(start.addEffort(hours(24)),
equalTo(IntraDayDate.create(today.plusDays(3), hours(3))));
assertThat(start.addEffort(hours(20)),
equalTo(IntraDayDate.create(today.plusDays(2), hours(7))));
assertThat(start.addEffort(hours(20).plus(minutes(20))),
equalTo(IntraDayDate.create(today.plusDays(2),
hours(7).plus(minutes(20)))));