### Question:
Week extends RegularTimePeriod implements Serializable { @Override public RegularTimePeriod previous() { Week result; if (this.week != FIRST_WEEK_IN_YEAR) { result = new Week(this.week - 1, this.year); } else { if (this.year > 1900) { int yy = this.year - 1; Calendar prevYearCalendar = Calendar.getInstance(); prevYearCalendar.set(yy, Calendar.DECEMBER, 31); result = new Week(prevYearCalendar.getActualMaximum( Calendar.WEEK_OF_YEAR), yy); } else { result = null; } } return result; } Week();  Week(int week, int year);  Week(int week, Year year);  Week(Date time);  Week(Date time, TimeZone zone, Locale locale); Year getYear(); int getYearValue(); int getWeek(); @Override long getFirstMillisecond(); @Override long getLastMillisecond(); @Override void peg(Calendar calendar); @Override RegularTimePeriod previous(); @Override RegularTimePeriod next(); @Override long getSerialIndex(); @Override long getFirstMillisecond(Calendar calendar); @Override long getLastMillisecond(Calendar calendar); @Override String toString(); @Override boolean equals(Object obj); @Override int hashCode(); @Override int compareTo(TimePeriod o1); static Week parseWeek(String s); static final int FIRST_WEEK_IN_YEAR; static final int LAST_WEEK_IN_YEAR; }### Answer:
@Test public void testW1Y1900Previous() { Week previous = (Week) this.w1Y1900.previous(); assertNull(previous); }
@Test public void testW52Y9999Previous() { Week previous = (Week) this.w52Y9999.previous(); assertEquals(this.w51Y9999, previous); }