[PATCH 08/11] selftests/damon: Test DAMON enabling with empty target_ids case

[SeongJae Park]

DAMON debugfs didn't check empty targets when starting monitoring, and
the issue is fixed with commit b5ca3e83ddb0 ("mm/damon/dbgfs: add
adaptive_targets list check before enable monitor_on").  To avoid future
regression, this commit adds a test case for that in DAMON selftests.

Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
 tools/testing/selftests/damon/debugfs_attrs.sh | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tools/testing/selftests/damon/debugfs_attrs.sh b/tools/testing/selftests/damon/debugfs_attrs.sh
index fc80380c59f0..d0916373f310 100644
--- a/tools/testing/selftests/damon/debugfs_attrs.sh
+++ b/tools/testing/selftests/damon/debugfs_attrs.sh
@@ -94,4 +94,13 @@ test_write_succ "$file" "" "$orig_content" "empty input"
 test_content "$file" "$orig_content" "" "empty input written"
 echo "$orig_content" > "$file"
 
+# Test empty targets case
+# =======================
+
+orig_target_ids=$(cat "$DBGFS/target_ids")
+echo "" > "$DBGFS/target_ids"
+orig_monitor_on=$(cat "$DBGFS/monitor_on")
+test_write_fail "$DBGFS/monitor_on" "on" "orig_monitor_on" "empty target ids"
+echo "$orig_target_ids" > "$DBGFS/target_ids"
+
 echo "PASS"
-- 
2.17.1