### Question:
QuarterUtils { public static TemporalAdjuster firstDayOfQuarterAdjuster() { return FIRST_DAY_OF_QUARTER_ADJUSTER; }  static boolean isFirstMonthOfQuarter(LocalDate date); static YearMonth getYearQuarter(int year, int quarter); static boolean isBeginOfQuarter(LocalDate date); static boolean isEndOfQuarter(LocalDate date); static int getQuarter(LocalDate date); static Month getFirstMonthOfQuarter(int quarter); static LocalDate getFirstDayOfQuarter(int year, int quarter); static LocalDate getFirstDayOfQuarter(int epochDay); static LocalDate getFirstDayOfQuarter(LocalDate date); static LocalDate getLastDayOfQuarter(int epochDay); static LocalDate getLastDayOfQuarter(LocalDate date); static LocalDate getLastDayOfQuarter(int year, int quarter); static CDateRange fromQuarter(int year, int quarter); static CDateRange fromDate(LocalDate date); static TemporalAdjuster nextQuarterAdjuster(); static TemporalAdjuster firstMonthInQuarterAdjuster(); static TemporalAdjuster firstDayOfQuarterAdjuster(); static TemporalAdjuster lastDayOfQuarterAdjuster();  }### Answer:
@Test void firstDayOfQuarterAdjuster() { assertThat(QuarterUtils.firstDayOfQuarterAdjuster().adjustInto(LocalDate.of(2018, 12, 25))) .isEqualTo(LocalDate.of(2018, 10, 1)); assertThat(QuarterUtils.firstDayOfQuarterAdjuster().adjustInto(LocalDateTime.of(2018, 2, 5, 5, 5))) .isEqualTo(LocalDateTime.of(2018, 1, 1, 5, 5)); }