test_that("ragged names blank all factor columns rather than filling partially", {
  d <- data.frame(sim = c("A_Rice_AWD_N120", "A-Rice-AWD-N30"),
                  stringsAsFactors = FALSE)
  r <- suppressWarnings(set_factors(d, parts = c("site", "crop", "water", "N")))
  expect_equal(r$site[1], "A")
  expect_true(is.na(r$site[2]))
})

test_that("numeric_from strips the prefix", {
  d <- data.frame(sim = c("A_N0", "A_N120"), stringsAsFactors = FALSE)
  r <- set_factors(d, parts = c("site", "N"), numeric_from = "N")
  expect_true(is.numeric(r$N)); expect_equal(sort(r$N), c(0, 120))
})

test_that("detect_factors finds the separator and constant fields", {
  s <- c("G_Rice_AWD_N0", "G_Rice_CF_N120", "B_Rice_AWD_N60")
  det <- detect_factors(s)
  expect_equal(det$sep, "_"); expect_equal(det$n_fields, 4)
  expect_true(2 %in% det$constant)
})