test_that("no dupes", {
  for (funcname in funcnames) {
    for (i in 1:20) {
      expect_equal(sum(duplicated(funcs[[funcname]](i, i - 1, seq_len(i)))), 0,
                  label = funcname)
    }
  }
})

test_that("all between 1 and n", {
  for (funcname in funcnames) {
    for (i in 1:20) {
      expect_true(all(funcs[[funcname]](i, i - 1, seq_len(i)) %in% seq_len(i)),
                  label = funcname)
    }
  }
})