mm/damon/core-test: add a unit test for damon_moving_sum()

Add a simple unit test for the pseudo moving-sum function
(damon_moving_sum()).

Link: https://lkml.kernel.org/r/20230915025251.72816-5-sj@kernel.orgSigned-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/core-test.h

@@ -341,6 +341,21 @@ static void damon_test_set_attrs(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, damon_set_attrs(c, &invalid_attrs), -EINVAL);
 }
 
+static void damon_test_moving_sum(struct kunit *test)
+{
+	unsigned int mvsum = 50000, nomvsum = 50000, len_window = 10;
+	unsigned int new_values[] = {10000, 0, 10000, 0, 0, 0, 10000, 0, 0, 0};
+	unsigned int expects[] = {55000, 50000, 55000, 50000, 45000, 40000,
+		45000, 40000, 35000, 30000};
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(new_values); i++) {
+		mvsum = damon_moving_sum(mvsum, nomvsum, len_window,
+				new_values[i]);
+		KUNIT_EXPECT_EQ(test, mvsum, expects[i]);
+	}
+}
+
 static void damos_test_new_filter(struct kunit *test)
 {
 	struct damos_filter *filter;
@@ -425,6 +440,7 @@ static struct kunit_case damon_test_cases[] = {
 	KUNIT_CASE(damon_test_set_regions),
 	KUNIT_CASE(damon_test_update_monitoring_result),
 	KUNIT_CASE(damon_test_set_attrs),
+	KUNIT_CASE(damon_test_moving_sum),
 	KUNIT_CASE(damos_test_new_filter),
 	KUNIT_CASE(damos_test_filter_out),
 	{},