test_that("is_date - test Sys.Date()", {
  expect_equal(is_date(Sys.Date()), TRUE)
})

test_that("is_date - test Sys.time()", {
  expect_equal(is_date(Sys.time()), TRUE)
})

test_that("is_date - test numeric", {
  expect_equal(is_date(10), FALSE)
})

test_that("is_date - test char", {
  expect_equal(is_date('20'), FALSE)
})

test_that("is_date - test char in Date format", {
  expect_equal(is_date('2024-12-01'), FALSE)
})

test_that('is_date - test only first element of vector', {
  expect_equal(is_date(c(Sys.Date(), 10)), TRUE)
})

test_that('is_date - test only first element of vector - 2', {
  expect_equal(is_date(c(10, Sys.Date())), FALSE)
})