test_that("christian", {
  expect_equal(christmas(2025), gregorian_date(2025, 12, 25))
  expect_equal(advent(2025), gregorian_date(2025, 11, 30))
  expect_equal(epiphany(2025), gregorian_date(2025, 1, 5))
  expect_equal(orthodox_christmas(2025), gregorian_date(2025, 1, 7))
  expect_equal(orthodox_christmas(1100), gregorian_date())
  expect_equal(easter(2025), gregorian_date(2025, 4, 20))
  expect_equal(astronomical_easter(2025), gregorian_date(2025, 4, 20))
  expect_equal(orthodox_easter(2025), gregorian_date(2025, 4, 20))
  expect_equal(pentecost(2025), gregorian_date(2025, 6, 8))
  expect_equal(easter(40), gregorian_date(40, 4, 15))
  expect_equal(orthodox_easter(40), gregorian_date(40, 4, 15))
  expect_equal(astronomical_easter(40), gregorian_date(40, 4, 15))
})