tests: Add lib/memcmp-test test case

Signed-off-by: Jakub Czapiga <jacz@semihalf.com>
Change-Id: Ib63123a36179127af4e3720ed01ca2611daa607e
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50785
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Fagerburg <pfagerburg@chromium.org>
diff --git a/tests/lib/Makefile.inc b/tests/lib/Makefile.inc
index 23d8d34..9f4a6ca 100644
--- a/tests/lib/Makefile.inc
+++ b/tests/lib/Makefile.inc
@@ -15,6 +15,7 @@
 tests-y += region_file-test
 tests-y += stack-test
 tests-y += memset-test
+tests-y += memcmp-test
 
 string-test-srcs += tests/lib/string-test.c
 string-test-srcs += src/lib/string.c
@@ -80,3 +81,6 @@
 
 memset-test-srcs += tests/lib/memset-test.c
 memset-test-srcs += src/lib/memset.c
+
+memcmp-test-srcs += tests/lib/memcmp-test.c
+
diff --git a/tests/lib/memcmp-test.c b/tests/lib/memcmp-test.c
new file mode 100644
index 0000000..f45b7f4
--- /dev/null
+++ b/tests/lib/memcmp-test.c
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/* Include memcmp() source code and alter its name to compare results with libc memcmp() */
+#define memcmp cb_memcmp
+
+#include "../lib/memcmp.c"
+
+#undef cb_memcmp
+
+#include <tests/test.h>
+#include <string.h>
+
+const char test_data1[] = "TEST_DATA @4321 !@#$%^&*\\/";
+const size_t test_data1_sz = sizeof(test_data1);
+
+const char test_data2[] = "TEST_DATA @8765 !@#$%^&*\\/";
+const char test_data2_sz = sizeof(test_data2);
+
+static void test_data_correctness(void **state)
+{
+	assert_int_equal(sizeof(test_data1), test_data1_sz);
+	assert_int_equal(sizeof(test_data2), test_data2_sz);
+	assert_int_equal(test_data1_sz, test_data2_sz);
+}
+
+static void test_memcmp_equal(void **state)
+{
+	const int res_cb = cb_memcmp(test_data1, test_data1, test_data1_sz);
+	const int res_std = memcmp(test_data1, test_data1, test_data1_sz);
+
+	assert_int_equal(0, res_cb);
+	assert_int_equal(res_cb, res_std);
+}
+
+static void test_memcmp_first_not_matching_lower(void **state)
+{
+	const int res_cb = cb_memcmp(test_data1, test_data2, test_data1_sz);
+	const int res_std = memcmp(test_data1, test_data2, test_data1_sz);
+
+	assert_true(res_cb < 0);
+	assert_int_equal(res_cb, res_std);
+}
+
+static void test_memcmp_first_not_matching_higher(void **state)
+{
+	const int res_cb = cb_memcmp(test_data2, test_data1, test_data1_sz);
+	const int res_std = memcmp(test_data2, test_data1, test_data1_sz);
+
+	assert_true(res_cb > 0);
+	assert_int_equal(res_cb, res_std);
+}
+
+static void test_memcmp_zero_size(void **state)
+{
+	const int res_cb = cb_memcmp(test_data1, test_data2, 0);
+	const int res_std = memcmp(test_data1, test_data2, 0);
+
+	assert_int_equal(0, res_cb);
+	assert_int_equal(res_cb, res_std);
+}
+
+int main(void)
+{
+	const struct CMUnitTest tests[] = {
+		cmocka_unit_test(test_data_correctness),
+		cmocka_unit_test(test_memcmp_equal),
+		cmocka_unit_test(test_memcmp_first_not_matching_lower),
+		cmocka_unit_test(test_memcmp_first_not_matching_higher),
+		cmocka_unit_test(test_memcmp_zero_size),
+	};
+
+	return cmocka_run_group_tests(tests, NULL, NULL);
+}