test_that("param validation works for exr_historical", {
  expect_error(exr_historical("202501-01"))
  expect_error(exr_historical(123))
})

test_that("param validation works for exr_convert", {
  expect_error(exr_convert("x", "USD", "EUR"))
  expect_error(exr_convert(-1, "USD", "EUR"))
  expect_error(exr_convert(1, 1, "EUR"))
  expect_error(exr_convert(1, "USD", 1))
  expect_error(exr_convert(1, "USD", "EUR", date = "2025/01/01"))
})