@Test public void convertDateTimeToMilliseconds() { Calendar calendar = Calendar.getInstance(); calendar.clear(); calendar.set(2014, 1, 1, 1, 1, 1); final TimeZone timeZone = calendar.getTimeZone(); long offset = timeZone.getOffset(calendar.getTime().getTime()); Long correctResult = offset + calendar.getTime().getTime(); assertEquals( highchartSeriesUtil.convertDateTimeToMilliseconds(calendar.getTime()), correctResult); }