Script that can detect failures in watch mode

scripts/test-watch-mode-works.sh

@@ -0,0 +1,28 @@
+#!/bin/sh
+
+out=$(mktemp)
+# make silent background
+npx mocha --watch 2>>$out.err 1>>$out &
+
+PID=$!
+#echo pid of mocha: $PID
+
+echo "Round 1" >> out
+touch src/fake-timers-src.js
+sleep 3
+echo "Round 2" >> out
+touch src/fake-timers-src.js
+sleep 2
+echo "Cleanup" >> out
+
+# Kill the process manually
+kill $PID >/dev/null
+kill -9 $PID >/dev/null
+
+#cat $out.err
+if grep failing $out; then
+    echo "This means some tests do not clean up after themselves or otherwise do not work in Mocha's watch mode"
+    echo "See $out for details or run $0 yourself"
+    exit 1
+fi
+exit 0