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

[Zhen Lei <thunder.leizhen@huawei.com>]

Test cases cover all possible situations:
1. The cut number is invalid: zero or negative
2. Partially cut.
3. Cut all.
4. The cut number is greater than the number of nodes in the old list.
5. The old list is empty.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
---
 lib/list-test.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/lib/list-test.c b/lib/list-test.c
index 37cbc33e9fdb380..3c60a6458545452 100644
--- a/lib/list-test.c
+++ b/lib/list-test.c
@@ -1172,6 +1172,56 @@ static void hlist_test_for_each_entry_safe(struct kunit *test)
 	KUNIT_EXPECT_TRUE(test, hlist_empty(&list));
 }
 
+static void hlist_test_cut_number(struct kunit *test)
+{
+	struct hlist_node a[4], *last;
+	HLIST_HEAD(old);
+	HLIST_HEAD(new);
+	int cnt;
+
+	hlist_add_head(&a[3], &old);
+	hlist_add_head(&a[2], &old);
+	hlist_add_head(&a[1], &old);
+	hlist_add_head(&a[0], &old);
+
+	/* The cut number is less than 0 or zero */
+	cnt = hlist_cut_number(&new, &old, -1, &last);
+	KUNIT_EXPECT_EQ(test, cnt, 0);
+	KUNIT_EXPECT_EQ(test, hlist_count_nodes(&old), 4);
+	cnt = hlist_cut_number(&new, &old, 0, &last);
+	KUNIT_EXPECT_EQ(test, cnt, 0);
+	KUNIT_EXPECT_EQ(test, hlist_count_nodes(&old), 4);
+
+	/* The cut number is less than the number of nodes in the old list. */
+	cnt = hlist_cut_number(&new, &old, 2, &last);
+	KUNIT_EXPECT_EQ(test, cnt, 2);
+	KUNIT_EXPECT_EQ(test, hlist_count_nodes(&old), 2);
+	KUNIT_EXPECT_EQ(test, hlist_count_nodes(&new), 2);
+	KUNIT_EXPECT_PTR_EQ(test, last, &a[1]);
+	hlist_splice_init(&new, last, &old);
+
+	/* The cut number is equal to the number of nodes in the old list. */
+	cnt = hlist_cut_number(&new, &old, 4, &last);
+	KUNIT_EXPECT_EQ(test, cnt, 4);
+	KUNIT_EXPECT_TRUE(test, hlist_empty(&old));
+	KUNIT_EXPECT_EQ(test, hlist_count_nodes(&new), 4);
+	KUNIT_EXPECT_PTR_EQ(test, last, &a[3]);
+	hlist_splice_init(&new, last, &old);
+
+	/* The cut number is greater than the number of nodes in the old list. */
+	cnt = hlist_cut_number(&new, &old, 5, &last);
+	KUNIT_EXPECT_EQ(test, cnt, 4);
+	KUNIT_EXPECT_TRUE(test, hlist_empty(&old));
+	KUNIT_EXPECT_EQ(test, hlist_count_nodes(&new), 4);
+	KUNIT_EXPECT_PTR_EQ(test, last, &a[3]);
+
+	/* The old list is empty. */
+	cnt = hlist_cut_number(&new, &old, 1, &last);
+	KUNIT_EXPECT_EQ(test, cnt, 0);
+	KUNIT_EXPECT_TRUE(test, hlist_empty(&old));
+	KUNIT_EXPECT_TRUE(test, hlist_empty(&new));
+}
+
 
 static struct kunit_case hlist_test_cases[] = {
 	KUNIT_CASE(hlist_test_init),
@@ -1192,6 +1242,7 @@ static struct kunit_case hlist_test_cases[] = {
 	KUNIT_CASE(hlist_test_for_each_entry_continue),
 	KUNIT_CASE(hlist_test_for_each_entry_from),
 	KUNIT_CASE(hlist_test_for_each_entry_safe),
+	KUNIT_CASE(hlist_test_cut_number),
 	{},
 };
 
-- 
2.34.1