def test_advanceBy(self):
# date = Date(0, 0, 0)
# date._julianDay = 0
# print(date._toGregorian())
# test plus
date = Date(1, 1, 2000)
julianDay = date.julianDay()
date.advanceBy(1)
newJulianDay = date.julianDay()
self.assertEqual(julianDay + 1, newJulianDay)
# test minus
date = Date(1, 1, 2000)
julianDay = date.julianDay()
date.advanceBy(-1)
newJulianDay = date.julianDay()
self.assertEqual(julianDay - 1, newJulianDay)
# test capped
date = Date(1, 1, 2000)
date.advanceBy(-999999999)
self.assertEqual(date.julianDay(), 0)
