[utest] implement rt_memcmp test cases

src/klibc/utest/TC_rt_memcmp.c

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2006-2024, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author             Notes
+ * 2020-05-06     Phillip Johnston   the first version
+ * 2024-12-24     Meco Man           port to utest
+ */
+
+#include <rtklibc.h>
+#include <utest.h>
+
+static rt_err_t utest_tc_init(void)
+{
+    return RT_EOK;
+}
+
+static rt_err_t utest_tc_cleanup(void)
+{
+    return RT_EOK;
+}
+
+static void TC_rt_memcmp_str(void)
+{
+    const char* s = "abc 123";
+
+    uassert_int_equal(rt_memcmp("abc", "abc", 4), 0);
+    uassert_int_equal(rt_memcmp(s, "abc", 3), 0);
+    uassert_int_equal(rt_memcmp("abc", s, 3), 0);
+
+    /* The following tests intentionally use a length > 3 */
+    /* To test what rt_memcmp does in such a situation */
+    uassert_int_equal(!!(rt_memcmp(s, "abc", 6) > 0), 1);
+    uassert_int_equal(!!(rt_memcmp("abc", s, 6) < 0), 1);
+
+    /* Check RT_NULL input handling */
+    uassert_int_not_equal(rt_memcmp("abc", RT_NULL, 3), 0);
+    uassert_int_not_equal(rt_memcmp(RT_NULL, "abc", 3), 0);
+
+    /* Check that two RT_NULL strings will match */
+    uassert_int_equal(rt_memcmp(RT_NULL, RT_NULL, 0), 0);
+}
+
+static void utest_do_tc(void)
+{
+    UTEST_UNIT_RUN(TC_rt_memcmp_str);
+}
+
+UTEST_TC_EXPORT(utest_do_tc, "klibc.rt_memcmp", utest_tc_init, utest_tc_cleanup, 1000);