tests/testthat/test-sum_code.R

In contrastable: Consistent Contrast Coding for Factors

test_that("sum_code and contr.sum are equivalent", {
  tst <- data.frame(fac = factor(c("a", "b", "c")))
  ref_mat <- matrix(c(1, -1, 0, 0, -1, 1), nrow = 3)
  colnames(ref_mat) <- c("a", "c")
  rownames(ref_mat) <- c("a", "b", "c")

  ref_cont <- enlist_contrasts(tst, fac ~ contr.sum + "b", verbose = FALSE)
  test_cont <- enlist_contrasts(tst, fac ~ sum_code + "b", verbose = FALSE)

  expect_equal(ref_cont, test_cont)
  expect_equal(test_cont[[1L]], ref_mat)
})