[PATCH v2 2/3] list: test: Add a test for list_is_head()

[David Gow]

list_is_head() was added recently[1], and didn't have a KUnit test. The
implementation is trivial, so it's not a particularly exciting test, but
it'd be nice to get back to full coverage of the list functions.

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/include/linux/list.h?id=0425473037db40d9e322631f2d4dc6ef51f97e88

Signed-off-by: David Gow <davidgow@xxxxxxxxxx>
---

Changes since v1:
https://lore.kernel.org/linux-kselftest/20220205061539.273330-2-davidgow@xxxxxxxxxx/
- Test both non-head elements of the same list and head elements of
  different lists.

---
 lib/list-test.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/lib/list-test.c b/lib/list-test.c
index 976e9ae1f3c5..1960615d1a9f 100644
--- a/lib/list-test.c
+++ b/lib/list-test.c
@@ -252,6 +252,23 @@ static void list_test_list_bulk_move_tail(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, i, 2);
 }
 
+static void list_test_list_is_head(struct kunit *test)
+{
+	struct list_head a, b, c;
+
+	/* Two lists: [a] -> b, [c] */
+	INIT_LIST_HEAD(&a);
+	INIT_LIST_HEAD(&c);
+	list_add_tail(&b, &a);
+
+	KUNIT_EXPECT_TRUE(test, list_is_head(&a, &a));
+	/* Non-head element of same list */
+	KUNIT_EXPECT_FALSE(test, list_is_head(&a, &b));
+	/* Head element of different list */
+	KUNIT_EXPECT_FALSE(test, list_is_head(&a, &c));
+}
+
+
 static void list_test_list_is_first(struct kunit *test)
 {
 	struct list_head a, b;
@@ -729,6 +746,7 @@ static struct kunit_case list_test_cases[] = {
 	KUNIT_CASE(list_test_list_move),
 	KUNIT_CASE(list_test_list_move_tail),
 	KUNIT_CASE(list_test_list_bulk_move_tail),
+	KUNIT_CASE(list_test_list_is_head),
 	KUNIT_CASE(list_test_list_is_first),
 	KUNIT_CASE(list_test_list_is_last),
 	KUNIT_CASE(list_test_list_empty),
-- 
2.35.0.263.gb82422642f-goog