test_that("can delete empty cache directory", {
  skip_if(getRversion() < package_version("4.0.0"))
  skip_on_cran()
  tmpdir <- withr::local_tempdir()
  withr::local_dir(tmpdir)
  dir.create("xxx")
  expect_true(delete_if_cache_directory(file.path(getwd(), "xxx")))
  dir.create("xxx")
  file.create("xxx/yyy")
  list.files("xxx")
  expect_false(delete_if_cache_directory(file.path(getwd(), "xxx")))
  expect_true(file.exists(tmpdir))
})