test_that('gh_delta works', {
  expect_equal(gh_delta(0L), c(90.0, 180.0))

  expect_equal(gh_delta(8L), c(8.58306884765625e-05, 0.000171661376953125))

  # one at a time, for now...
  expect_error(gh_delta(1:5), 'One precision at a time', fixed = TRUE)
})