From 29d16a7be926190a2c845dd6671e10c017cc8592 Mon Sep 17 00:00:00 2001
From: Emil Hvitfeldt <emilhhvitfeldt@gmail.com>
Date: Tue, 21 Jan 2025 15:36:56 -0800
Subject: [PATCH 1/4] refactor out `check_sparse_arg()`

---
 R/dummy.R | 1 -
 1 file changed, 1 deletion(-)

diff --git a/R/dummy.R b/R/dummy.R
index 854f4aaa9..b90cd7ba1 100644
--- a/R/dummy.R
+++ b/R/dummy.R
@@ -182,7 +182,6 @@ prep.step_dummy <- function(x, training, info = NULL, ...) {
   check_type(training[, col_names], types = c("factor", "ordered"))
   check_bool(x$one_hot, arg = "one_hot")
   check_function(x$naming, arg = "naming", allow_empty = FALSE)
-  rlang::arg_match0(x$sparse, c("auto", "yes", "no"), arg_nm = "sparse")
 
   if (length(col_names) > 0) {
     ## I hate doing this but currently we are going to have

From 1c256341a87a3b67aab50e94d070d482da3e667f Mon Sep 17 00:00:00 2001
From: Emil Hvitfeldt <emilhhvitfeldt@gmail.com>
Date: Tue, 21 Jan 2025 15:41:58 -0800
Subject: [PATCH 2/4] add sparse_is_yes()

---
 R/sparsevctrs.R | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/R/sparsevctrs.R b/R/sparsevctrs.R
index 164fa2e1f..3a976bc80 100644
--- a/R/sparsevctrs.R
+++ b/R/sparsevctrs.R
@@ -111,3 +111,13 @@ is_sparse_matrix <- function(x) {
 
   zeroes / (n_rows * n_cols)
 }
+
+check_sparse_arg <- function(x) {
+  if (!is.null(x)) {
+    rlang::arg_match0(x, c("auto", "yes", "no"), arg_nm = "sparse")
+  }
+}
+
+sparse_is_yes <- function(x) {
+  !is.null(x) && x == "yes"
+}
\ No newline at end of file

From 2be6b7ed6425b84276031f98c14ff339d3dccf57 Mon Sep 17 00:00:00 2001
From: Emil Hvitfeldt <emilhhvitfeldt@gmail.com>
Date: Tue, 21 Jan 2025 15:42:06 -0800
Subject: [PATCH 3/4] use and test helper functions

---
 R/dummy.R                   |  3 ++-
 tests/testthat/test-dummy.R | 17 +++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/R/dummy.R b/R/dummy.R
index b90cd7ba1..3ea7c58fb 100644
--- a/R/dummy.R
+++ b/R/dummy.R
@@ -182,6 +182,7 @@ prep.step_dummy <- function(x, training, info = NULL, ...) {
   check_type(training[, col_names], types = c("factor", "ordered"))
   check_bool(x$one_hot, arg = "one_hot")
   check_function(x$naming, arg = "naming", allow_empty = FALSE)
+  check_sparse_arg(x$sparse)
 
   if (length(col_names) > 0) {
     ## I hate doing this but currently we are going to have
@@ -301,7 +302,7 @@ bake.step_dummy <- function(object, new_data, ...) {
       ordered = is_ordered
     )
 
-    if (object$sparse == "yes") {
+    if (sparse_is_yes(object$sparse)) {
       current_contrast <- getOption("contrasts")[is_ordered + 1]
       if (!current_contrast %in% c("contr.treatment", "contr_one_hot")) {
         cli::cli_abort(
diff --git a/tests/testthat/test-dummy.R b/tests/testthat/test-dummy.R
index 1175d89c9..e51c8a3c4 100644
--- a/tests/testthat/test-dummy.R
+++ b/tests/testthat/test-dummy.R
@@ -382,6 +382,23 @@ test_that("sparse = 'yes' errors on unsupported contrasts", {
   )
 })
 
+test_that("sparse argument is backwards compatible", {
+  dat <- tibble(x = c(letters))
+  rec <- recipe(~ ., data = dat) %>%
+    step_dummy(x) %>%
+    prep()
+
+  exp <- bake(rec, dat)
+
+  # Simulate old recipe
+  rec$steps[[1]]$sparse <- NULL
+
+  expect_identical(
+    bake(rec, dat),
+    exp
+  )
+})
+
 test_that(".recipes_toggle_sparse_args works", {
   rec <- recipe(~., iris) %>%
     step_dummy(all_nominal_predictors())

From 7dacb51d032a16510be5ef6c9cc715d28c9421a1 Mon Sep 17 00:00:00 2001
From: Emil Hvitfeldt <emilhhvitfeldt@gmail.com>
Date: Tue, 21 Jan 2025 15:57:28 -0800
Subject: [PATCH 4/4] add check_sparse_arg to test-skipping

---
 tests/testthat/test-skipping.R | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/testthat/test-skipping.R b/tests/testthat/test-skipping.R
index 838dd20fe..7a8a8d34a 100644
--- a/tests/testthat/test-skipping.R
+++ b/tests/testthat/test-skipping.R
@@ -46,6 +46,7 @@ test_that("check existing steps for `skip` arg", {
   step_check <- step_check[step_check != "check_role_requirements"]
   step_check <- step_check[step_check != "check_bake_role_requirements"]
   step_check <- step_check[step_check != "check_step_check_args"]
+  step_check <- step_check[step_check != "check_sparse_arg"]
 
   # R/import-standalone-types-check.R
   step_check <- step_check[step_check != "check_bool"]