[PATCH v3 3/3] list: test: Add a test for list_entry_is_head()

[David Gow]

The list_entry_is_head() macro was added[1] after the list KUnit tests,
so wasn't tested. Add a new KUnit test to complete the set.

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e130816164e244b692921de49771eeb28205152d

Signed-off-by: David Gow <davidgow@xxxxxxxxxx>
Acked-by: Daniel Latypov <dlatypov@xxxxxxxxxx>
Acked-by: Brendan Higgins <brendanhiggins@xxxxxxxxxx>
---

Changes since v2:
https://lore.kernel.org/linux-kselftest/20220208040122.695258-3-davidgow@xxxxxxxxxx/
- Use the _MSG variants of the assert macros, as suggested by Daniel
  Latypov.
Changes since v1:
https://lore.kernel.org/linux-kselftest/20220205061539.273330-3-davidgow@xxxxxxxxxx/
- Rework the test entirely to better match the improved list_is_head()
  test.

---
 lib/list-test.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/lib/list-test.c b/lib/list-test.c
index 19f13059439b..869caae14b10 100644
--- a/lib/list-test.c
+++ b/lib/list-test.c
@@ -548,6 +548,26 @@ static void list_test_list_entry(struct kunit *test)
 				struct list_test_struct, list));
 }
 
+static void list_test_list_entry_is_head(struct kunit *test)
+{
+	struct list_test_struct test_struct1, test_struct2, test_struct3;
+
+	INIT_LIST_HEAD(&test_struct1.list);
+	INIT_LIST_HEAD(&test_struct3.list);
+
+	list_add_tail(&test_struct2.list, &test_struct1.list);
+
+	KUNIT_EXPECT_TRUE_MSG(test,
+		list_entry_is_head((&test_struct1), &test_struct1.list, list),
+		"Head element of same list");
+	KUNIT_EXPECT_FALSE_MSG(test,
+		list_entry_is_head((&test_struct2), &test_struct1.list, list),
+		"Non-head element of same list");
+	KUNIT_EXPECT_FALSE_MSG(test,
+		list_entry_is_head((&test_struct3), &test_struct1.list, list),
+		"Head element of different list");
+}
+
 static void list_test_list_first_entry(struct kunit *test)
 {
 	struct list_test_struct test_struct1, test_struct2;
@@ -763,6 +783,7 @@ static struct kunit_case list_test_cases[] = {
 	KUNIT_CASE(list_test_list_splice_init),
 	KUNIT_CASE(list_test_list_splice_tail_init),
 	KUNIT_CASE(list_test_list_entry),
+	KUNIT_CASE(list_test_list_entry_is_head),
 	KUNIT_CASE(list_test_list_first_entry),
 	KUNIT_CASE(list_test_list_last_entry),
 	KUNIT_CASE(list_test_list_first_entry_or_null),
-- 
2.35.0.263.gb82422642f-goog