@Test public void testHasValidPeriod_noDates() { assertFalse(timeTracker.hasValidPeriod()); }
boolean hasValidPeriod() { return intervalStop >= intervalStart; }
TimeTracker { boolean hasValidPeriod() { return intervalStop >= intervalStart; } }
TimeTracker { boolean hasValidPeriod() { return intervalStop >= intervalStart; } TimeTracker(); }
TimeTracker { boolean hasValidPeriod() { return intervalStop >= intervalStart; } TimeTracker();  }
TimeTracker { boolean hasValidPeriod() { return intervalStop >= intervalStart; } TimeTracker();   }