Improve message; add test

Author: hadley

R/parallel.R

@@ -46,9 +46,7 @@ test_files_parallel <- function(
   # TODO: support timeouts. 20-30s for each file by default?
 
   num_workers <- min(default_num_cpus(), length(test_paths))
-  cli::cli_inform(
-    "Starting {num_workers} test process{?es}."
-  )
+  cli::cli_inform("Starting {num_workers} test process{?es}.")
 
   # Set up work queue ------------------------------------------
   queue <- NULL
@@ -107,7 +105,10 @@ default_num_cpus <- function() {
   if (!is.null(ncpus)) {
     ncpus <- suppressWarnings(as.integer(ncpus))
     if (is.na(ncpus)) {
-      cli::cli_abort("{.fn getOption}({.arg Ncpus}) must be an integer.")
+      cli::cli_abort(
+        "{.code getOption('Ncpus')} must be an integer.",
+        call = NULL
+      )
     }
     return(ncpus)
   }

tests/testthat/_snaps/parallel.md

@@ -0,0 +1,8 @@
+# good error if bad option
+
+    Code
+      default_num_cpus()
+    Condition
+      Error:
+      ! `getOption('Ncpus')` must be an integer.
+

tests/testthat/test-parallel.R

@@ -20,6 +20,11 @@ test_that("detect number of cpus to use", {
   expect_equal(default_num_cpus(), 13L)
 })
 
+test_that("good error if bad option", {
+  withr::local_options(Ncpus = "bad")
+  expect_snapshot(default_num_cpus(), error = TRUE)
+})
+
 test_that("ok", {
   withr::local_envvar(c(TESTTHAT_PARALLEL = "TRUE"))
   # we cannot run these with the silent reporter, because it is not