test_that("make_rel() function test", {
  expect_equal(make_rel(c(1, 2, 3)), c(0, 0.5, 1))
  expect_equal(make_rel(c(10, 20, 30)), c(0, 0.5, 1))
})

test_that("make_rel() gives correct output", {
  rel <- make_rel(c(-1000, -1, 0, 1, 10))
  expect_equal(range(rel), c(0, 1))
  expect_equal(round(make_rel(c(965.86, 82.75, -458.28, -0.98, -62.94)), 4),
               c(1.0000, 0.3799, 0.0000, 0.3211, 0.2776))
})

test_that("make_rel() gives correct output with OpenSpecy objects", {
  data("raman_hdpe")
  rel <- make_rel(raman_hdpe) |> expect_silent()

  expect_s3_class(rel, "OpenSpecy")
  expect_true(check_OpenSpecy(rel))
  
  expect_equal(range(rel$spectra), c(0, 1))
})