ARROW-8375: [CI][R] Make Windows tests more verbose in case of segfault

The verbose output will at least tell us what was being run when the crash happened.

Closes #6878 from nealrichardson/r-windows-tests

Authored-by: Neal Richardson <neal.p.richardson@gmail.com>
Signed-off-by: Neal Richardson <neal.p.richardson@gmail.com>

.github/workflows/r.yml

@@ -155,6 +155,12 @@ jobs:
         uses: actions/checkout@v2
         with:
           fetch-depth: 0
+      - name: Make R tests verbose
+        shell: cmd
+        run: |
+          cd r/tests
+          sed -i.bak -E -e 's/"arrow"/"arrow", reporter = "location"/' testthat.R
+          rm -f testthat.R.bak
       - name: Fetch Submodules and Tags
         shell: bash
         run: ci/scripts/util_checkout.sh

r/tests/testthat/helper-arrow.R

@@ -18,6 +18,11 @@
 # Wrap testthat::test_that with a check for the C++ library
 options(..skip.tests = !arrow:::arrow_available())
 
+if (tolower(Sys.info()[["sysname"]]) == "windows") {
+  # See if this stabilizes tests; TODO fix the underlying issue
+  options(arrow.use_threads = FALSE)
+}
+
 test_that <- function(what, code) {
   testthat::test_that(what, {
     skip_if(getOption("..skip.tests", TRUE), "arrow C++ library not available")