fix: allow to test on windows

tags: fix

Why?

- hostname is check on the machine, but does not exist on windows machine

What?

- If hostname is empty after system command, then changed to windows

Author: statnmap

Diff for: R/cran_check_unique.R

@@ -47,6 +47,7 @@ check_unique <- function(check_dir, lib_dir, scratch, Ncpus) {
   # Ncpus <- 6
 
   hostname <- system2("hostname", "-f", stdout = TRUE)
+  if (length(hostname) == 0) {hostname <- "windows"}
   if(hostname == "xmanduin.wu.ac.at") {
     Sys.setenv("_R_CHECK_EXAMPLE_TIMING_THRESHOLD_" = "10")
     Ncpus <- 10