[PATCH i-g-t v9 06/49] lib/tests: Add tests for array manipulations

[Louis Chauvet <louis.chauvet@bootlin.com>]

As array manipulation functions are not trivial, add few tests to ensure
they work properly.

Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
 lib/tests/igt_kms_array_diff.c | 159 +++++++++++++++++++++++++++++++++++++++++
 lib/tests/meson.build          |   1 +
 2 files changed, 160 insertions(+)

diff --git a/lib/tests/igt_kms_array_diff.c b/lib/tests/igt_kms_array_diff.c
new file mode 100644
index 000000000000..ebdc3b62bc31
--- /dev/null
+++ b/lib/tests/igt_kms_array_diff.c
@@ -0,0 +1,159 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2026 Google
+ *
+ * Authors:
+ *   Louis Chauvet <louis.chauvet@bootlin.com> (assisted by MistralAI)
+ */
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "drmtest.h"
+#include "igt_core.h"
+#include "igt_kms.h"
+
+/**
+ * TEST: get_array_diff
+ * Category: Core
+ * Description: Test the get_array_diff() function
+ *
+ * SUBTEST: get_array_diff-empty-both
+ * Description: Test with both arrays empty
+ *
+ * SUBTEST: get_array_diff-empty-a
+ * Description: Test with array_a empty
+ *
+ * SUBTEST: get_array_diff-empty-b
+ * Description: Test with array_b empty
+ *
+ * SUBTEST: get_array_diff-no-diff
+ * Description: Test with identical arrays (no difference)
+ *
+ * SUBTEST: get_array_diff-full-diff
+ * Description: Test with completely different arrays
+ *
+ * SUBTEST: get_array_diff-partial-diff
+ * Description: Test with partial overlap between arrays
+ *
+ * SUBTEST: get_array_diff-null-diff
+ * Description: Test with diff parameter set to NULL (count only)
+ */
+
+static void test_get_array_diff_empty_both(void)
+{
+	uint32_t *diff = NULL;
+	int diff_len;
+
+	diff_len = get_array_diff(NULL, 0, NULL, 0, &diff);
+	igt_assert_eq(diff_len, 0);
+	free(diff);
+}
+
+static void test_get_array_diff_empty_a(void)
+{
+	uint32_t array_b[] = {1, 2, 3};
+	uint32_t *diff = NULL;
+	int diff_len;
+
+	diff_len = get_array_diff(NULL, 0, array_b, ARRAY_SIZE(array_b), &diff);
+	igt_assert_eq(diff_len, 0);
+	free(diff);
+}
+
+static void test_get_array_diff_empty_b(void)
+{
+	uint32_t array_a[] = {1, 2, 3};
+	uint32_t *diff = NULL;
+	int diff_len;
+
+	diff_len = get_array_diff(array_a, ARRAY_SIZE(array_a), NULL, 0, &diff);
+	igt_assert_eq(diff_len, 3);
+	igt_assert(diff);
+	igt_assert_eq(diff[0], 1);
+	igt_assert_eq(diff[1], 2);
+	igt_assert_eq(diff[2], 3);
+	free(diff);
+}
+
+static void test_get_array_diff_no_diff(void)
+{
+	uint32_t array_a[] = {1, 2, 3};
+	uint32_t array_b[] = {1, 2, 3};
+	uint32_t *diff = NULL;
+	int diff_len;
+
+	diff_len = get_array_diff(array_a, ARRAY_SIZE(array_a), array_b, ARRAY_SIZE(array_b),
+				  &diff);
+	igt_assert_eq(diff_len, 0);
+	free(diff);
+}
+
+static void test_get_array_diff_full_diff(void)
+{
+	uint32_t array_a[] = {1, 2, 3};
+	uint32_t array_b[] = {4, 5, 6};
+	uint32_t *diff = NULL;
+	int diff_len;
+
+	diff_len = get_array_diff(array_a, ARRAY_SIZE(array_a), array_b, ARRAY_SIZE(array_b),
+				  &diff);
+	igt_assert_eq(diff_len, 3);
+	igt_assert(diff);
+	igt_assert_eq(diff[0], 1);
+	igt_assert_eq(diff[1], 2);
+	igt_assert_eq(diff[2], 3);
+	free(diff);
+}
+
+static void test_get_array_diff_partial_diff(void)
+{
+	uint32_t array_a[] = {1, 2, 3, 4, 5};
+	uint32_t array_b[] = {2, 3, 6};
+	uint32_t *diff = NULL;
+	int diff_len;
+
+	diff_len = get_array_diff(array_a, ARRAY_SIZE(array_a), array_b, ARRAY_SIZE(array_b),
+				  &diff);
+	igt_assert_eq(diff_len, 3);
+	igt_assert(diff);
+	igt_assert_eq(diff[0], 1);
+	igt_assert_eq(diff[1], 4);
+	igt_assert_eq(diff[2], 5);
+	free(diff);
+}
+
+static void test_get_array_diff_null_diff(void)
+{
+	uint32_t array_a[] = {1, 2, 3};
+	uint32_t array_b[] = {2, 3};
+	int diff_len;
+
+	diff_len = get_array_diff(array_a, ARRAY_SIZE(array_a), array_b, ARRAY_SIZE(array_b), NULL);
+	igt_assert_eq(diff_len, 1);
+}
+
+IGT_TEST_DESCRIPTION("Test get_array_diff() function");
+int igt_main()
+{
+	igt_subtest("get_array_diff-empty-both")
+		test_get_array_diff_empty_both();
+
+	igt_subtest("get_array_diff-empty-a")
+		test_get_array_diff_empty_a();
+
+	igt_subtest("get_array_diff-empty-b")
+		test_get_array_diff_empty_b();
+
+	igt_subtest("get_array_diff-no-diff")
+		test_get_array_diff_no_diff();
+
+	igt_subtest("get_array_diff-full-diff")
+		test_get_array_diff_full_diff();
+
+	igt_subtest("get_array_diff-partial-diff")
+		test_get_array_diff_partial_diff();
+
+	igt_subtest("get_array_diff-null-diff")
+		test_get_array_diff_null_diff();
+}
diff --git a/lib/tests/meson.build b/lib/tests/meson.build
index 124a9ecae84d..f1db66d07c28 100644
--- a/lib/tests/meson.build
+++ b/lib/tests/meson.build
@@ -13,6 +13,7 @@ lib_tests = [
 	'igt_fork_helper',
 	'igt_hook',
 	'igt_hook_integration',
+	'igt_kms_array_diff',
         'igt_ktap_parser',
 	'igt_list_only',
 	'igt_invalid_subtest_name',

-- 
2.52.0