utest: move cpp from examples to components/libc/cplusplus

Also update the case names to compatible with naming rules.

Signed-off-by: Chen Wang <unicorn_wang@outlook.com>

components/libc/cplusplus/utest/tc_mutex.cpp

@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2006-2025, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2025-09-19     Rbb666       the first version
+ */
+
+#include <rtthread.h>
+#include "utest.h"
+#include <thread>
+#include <mutex>
+#include <chrono>
+
+/**
+ * @brief Test basic mutex operations with lock_guard.
+ */
+static void test_mutex(void)
+{
+    std::mutex m;
+    int        count = 0;
+    auto       func  = [&]() mutable {
+        std::lock_guard<std::mutex> lock(m);
+        for (int i = 0; i < 1000; ++i)
+        {
+            ++count;
+        }
+    };
+
+    std::thread t1(func);
+    std::thread t2(func);
+
+    t1.join();
+    t2.join();
+
+    uassert_int_equal(count, 2000);
+}
+
+/**
+ * @brief Test recursive mutex allowing multiple locks by the same thread.
+ */
+static void test_recursive_mutex(void)
+{
+    std::recursive_mutex rm;
+    int                  count = 0;
+    auto                 func  = [&]() mutable {
+        std::lock_guard<std::recursive_mutex> lock1(rm);
+        std::lock_guard<std::recursive_mutex> lock2(rm);
+        for (int i = 0; i < 1000; ++i)
+        {
+            ++count;
+        }
+    };
+
+    std::thread t1(func);
+    std::thread t2(func);
+
+    t1.join();
+    t2.join();
+
+    if (count != 2000)
+    {
+        uassert_false(true);
+    }
+    uassert_true(true);
+}
+
+/**
+ * @brief Test try_lock on mutex.
+ */
+static void test_try_lock(void)
+{
+    std::mutex m;
+    if (m.try_lock())
+    {
+        m.unlock();
+        uassert_true(true);
+    }
+    else
+    {
+        uassert_false(true);
+    }
+}
+
+/**
+ * @brief Test locking multiple mutexes with std::lock.
+ */
+static void test_lock_multiple(void)
+{
+    std::mutex m1, m2;
+    std::lock(m1, m2);
+    m1.unlock();
+    m2.unlock();
+    uassert_true(true);
+}
+
+static rt_err_t utest_tc_init(void)
+{
+    return RT_EOK;
+}
+
+static rt_err_t utest_tc_cleanup(void)
+{
+    return RT_EOK;
+}
+
+static void testcase(void)
+{
+    /* Test basic mutex operations with lock_guard */
+    UTEST_UNIT_RUN(test_mutex);
+    /* Test recursive mutex allowing multiple locks by the same thread */
+    UTEST_UNIT_RUN(test_recursive_mutex);
+    /* Test try_lock on mutex */
+    UTEST_UNIT_RUN(test_try_lock);
+    /* Test locking multiple mutexes with std::lock */
+    UTEST_UNIT_RUN(test_lock_multiple);
+}
+UTEST_TC_EXPORT(testcase, "components.libc.cpp.mutex_tc", utest_tc_init, utest_tc_cleanup, 10);