test_that("is_composite returns true for registered composites and false for primitives", {
  expect_true(myIO:::is_composite("boxplot"))
  expect_true(myIO:::is_composite("violin"))
  expect_true(myIO:::is_composite("ridgeline"))
  expect_false(myIO:::is_composite("line"))
  expect_false(myIO:::is_composite("banana"))
})

test_that("expandComposite errors on unknown composite type", {
  expect_error(
    myIO:::expandComposite("banana", data.frame(), list(), "label", NULL, list()),
    "Unknown composite type"
  )
})