test_that("Conversion to degrees", {
  expect_equal(convert2degrees(pi/2), 90)
  expect_equal(convert2degrees(90, input="degrees"), 90)
})

test_that("Conversion to radians", {
  expect_equal(convert2radians(90), pi/2)
  expect_equal(convert2radians(pi/2, input="radians"), pi/2)
})

test_that("Reject unknown input", {
  expect_error(convert2degrees(90, input="tuna"), "Unknown input to convert2degrees: tuna")
  expect_error(convert2radians(90, input="garlic"), "Unknown input to convert2radians: garlic")
})