add disclaimer for ncores on Windows in tests, prevent SCUT_parallel …

…example from triggering a warning

R/scut.R

@@ -105,7 +105,9 @@ SCUT <- function(data, cls_col, oversample = oversample_smote,
 #' @importFrom parallel detectCores mclapply
 #'
 #' @examples
-#' ret <- SCUT_parallel(wine, "type", ncores = 2, undersample = undersample_kmeans)
+#' # SCUT_parallel fires a warning if ncores > 1 on Windows and will run on
+#' # one core only.
+#' ret <- SCUT_parallel(wine, "type", ncores = 1, undersample = undersample_kmeans)
 #' table(ret$type)
 SCUT_parallel <- function(data, cls_col, ncores = detectCores() %/% 2,
                           oversample = oversample_smote,
@@ -115,8 +117,7 @@ SCUT_parallel <- function(data, cls_col, ncores = detectCores() %/% 2,
 
   # windows does not support mclapply, so we have to do this serially
   if (.Platform$OS.type == "windows") {
-    warning("SCUT_parallel is not supported on Windows and will run on
-             one core.")
+    warning("SCUT_parallel runs on one core only on Windows.")
     ncores <- 1
   }
 

tests/testthat/test-scut.R

@@ -28,10 +28,7 @@ for (i in 1:length(undersamplers)) {
 
   test_that(paste(osamp, usamp, "(parallel) have equal class distribution"),
             {
-              # During R CMD check, doParallel sometimes fails to export the
-              # package to parallel workers on Windows. This is not a problem
-              # once the package is installed, so the parallel version is
-              # skipped on Windows.
+              # Skip to avoid triggering a warning on > 1 core
               skip_on_os("windows")
 
 
@@ -52,7 +49,7 @@ for (i in 1:length(undersamplers)) {
 if (.Platform$OS.type == "windows") {
   expect_warning(
     SCUT_parallel(wine, "type"),
-    regexp=""
+    regexp="SCUT_parallel runs on one core only on Windows."
   )
 }