run tests on all changed dirs

internal/kokoro/presubmit.sh

@@ -90,14 +90,15 @@ fi
 CHANGED_DIRS=$(echo "$SIGNIFICANT_CHANGES" | tr ' ' '\n' | cut -d/ -f1 | sort -u |
   tr '\n' ' ' | xargs ls -d 2>/dev/null || true)
 
-# Check if "." is in the list of changed directories, filter other directories if so.
-if echo "$CHANGED_DIRS" | grep -qw "\."; then
-  echo "Detected changes in the root directory, running tests in all submodules"
-  CHANGED_DIRS="."
-fi
-
 echo "Running tests only in changed submodules: $CHANGED_DIRS"
 for d in $CHANGED_DIRS; do
+  # Check if "." is in the list of changed directories, which means the root
+  if [ $d == "." ]; then
+    pushd $(dirname $i)
+    runPresubmitTests
+    popd
+    continue
+  fi
   for i in $(find "$d" -name go.mod); do
     pushd $(dirname $i)
     runPresubmitTests