wages_monotonic <- wages %>%
  features(ln_wages, feat_monotonic)

test_that("feat_monotonic returns the right names", {
  expect_equal(
    names(wages_monotonic),
    c("id", "increase", "decrease", "unvary", "monotonic")
  )
})


test_that("feat_monotonic returns the right dimensions", {
  expect_equal(dim(wages_monotonic), c(888, 5))
})

library(dplyr)
test_that("feat_monotonic returns all ids", {
  expect_equal(n_distinct(wages_monotonic$id), 888)
})