test_that("to_integer works", {
  expect_identical(fwildclusterboot:::to_integer(c("a", "b", "c")), 1:3)
  expect_identical(fwildclusterboot:::to_integer(1:3), 1:3)
  expect_identical(fwildclusterboot:::to_integer(2:4), 1:3)
  expect_identical(fwildclusterboot:::to_integer(factor(c(1, 2, 3))), 1:3)
})