utest: keep testcase failures across units

[CYFS3]

拉取/合并请求描述（PR description）

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为什么提交这份PR (why to submit this PR)

修复 utest testcase 汇总误判问题：当一个 testcase 内部包含多个 UTEST_UNIT_RUN 时，某个 unit 失败后，如果后续 unit 通过，会因为 utest_unit_run() 重置 local_utest.failed_num，导致 testcase 和最终汇总仍显示通过。

你的解决方案是什么 (what is your solution)

在 testcase 开始执行前清零统计；每个 unit 仍保持独立统计，unit 执行结束后将本 unit 的 pass/fail 数累加回 testcase 总计。这样可以保留 unit 级隔离，同时保证 testcase 级失败不会被后续 unit 覆盖。

请提供验证的bsp和config (provide the config and bsp)

• BSP: bsp/qemu-vexpress-a9

• .config: CONFIG_RT_USING_UTEST=y，CONFIG_RT_USING_UTESTCASES=y

• action: 本地环境缺少可用交叉编译工具链，未触发 action；已执行 git diff --check

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当前拉取/合并请求的状态 Intent for your PR

必须选择一项 Choose one (Mandatory):

• 本拉取/合并请求是一个草稿版本 This PR is for a code-review and is intended to get feedback
• 本拉取/合并请求是一个成熟版本 This PR is mature, and ready to be integrated into the repo

代码质量 Code Quality：

我在这个拉取/合并请求中已经考虑了 As part of this pull request, I have considered the following:

• 已经仔细查看过代码改动的对比 Already check the difference between PR and old code
• 代码风格正确，包括缩进空格，命名及其他风格 Style guide is adhered to, including spacing, naming and other styles
• 没有冗余代码，代码尽量精简，不包含#if 0代码，不包含已经被注释了的代码 All redundant code is removed and cleaned up
• 所有变更均有原因及合理的，并且不会影响到其他软件组件代码或BSP All modifications are justified and not affect other components or BSP
• 对难懂代码均提供对应的注释 I have commented appropriately where code is tricky
• 代码是高质量的 Code in this PR is of high quality
• 已经使用formatting等源码格式化工具确保格式符合RT-Thread代码规范 This PR complies with RT-Thread code specification
• 如果是新增BSP，已经添加ci检查到 ALL_BSP_COMPILE.json

[github-actions]

📌 Code Review Assignment

🏷️ Tag: components

Reviewers: @Maihuanyi

Changed Files (Click to expand)

• components/net/utest/tc_netdev.c
• components/utilities/utest/utest.c

🏷️ Tag: kernel

Reviewers: @GorrayLi @ReviewSun @hamburger-os @lianux-mm @wdfk-prog @xu18838022837

Changed Files (Click to expand)

• src/utest/signal_tc.c

---

📊 Current Review Status (Last Updated: 2026-07-14 11:34 CST)

• ⌛ @GorrayLi Pending Review
• ⌛ @Maihuanyi Pending Review
• ⌛ @ReviewSun Pending Review
• ⌛ @hamburger-os Pending Review
• ⌛ @lianux-mm Pending Review
• ⌛ @wdfk-prog Pending Review
• ⌛ @xu18838022837 Pending Review

---

📝 Review Instructions

1. 维护者可以通过单击此处来刷新审查状态: 🔄 刷新状态
   Maintainers can refresh the review status by clicking here: 🔄 Refresh Status

2. 确认审核通过后评论 LGTM/lgtm
   Comment LGTM/lgtm after confirming approval

3. PR合并前需至少一位维护者确认
   PR must be confirmed by at least one maintainer before merging

ℹ️ 刷新CI状态操作需要具备仓库写入权限。
ℹ️ Refresh CI status operation requires repository Write permission.

[github-actions]

👋 感谢您对 RT-Thread 的贡献！Thank you for your contribution to RT-Thread!

为确保代码符合 RT-Thread 的编码规范，请在你的仓库中执行以下步骤运行代码格式化工作流（如果格式化CI运行失败）。
To ensure your code complies with RT-Thread's coding style, please run the code formatting workflow by following the steps below (If the formatting of CI fails to run).

---

🛠 操作步骤 | Steps

1. 前往 Actions 页面 | Go to the Actions page
   点击进入工作流 → | Click to open workflow →

2. 点击 Run workflow | Click Run workflow

• 设置需排除的文件/目录（目录请以"/"结尾）
  Set files/directories to exclude (directories should end with "/")
• 将目标分支设置为 \ Set the target branch to：fix/utest-unit-failure-count
• 设置PR number为 \ Set the PR number to：11601

3. 等待工作流完成 | Wait for the workflow to complete
   格式化后的代码将自动推送至你的分支。
   The formatted code will be automatically pushed to your branch.

完成后，提交将自动更新至 fix/utest-unit-failure-count 分支，关联的 Pull Request 也会同步更新。
Once completed, commits will be pushed to the fix/utest-unit-failure-count branch automatically, and the related Pull Request will be updated.

如有问题欢迎联系我们，再次感谢您的贡献！💐
If you have any questions, feel free to reach out. Thanks again for your contribution!

[github-actions]

MemBrowse Memory Report

k230

• SRAM: .eh_frame +88 B (+0.0%, 1,122,683 B / 268,300,288 B, total: 0% used)

loongson-ls1cdev

• Code: .text +128 B (+0.0%, 362,624 B)

nuvoton-m487

• CODE: .text +104 B (+0.0%, 355,772 B / 524,288 B, total: 68% used)

qemu-virt64-aarch64

• Code: .eh_frame +8 B (+0.0%, 1,056,372 B)
• Data: .data -8 B (-0.0%, 517,376 B)

simulator

• Code: .text +27 B (+0.0%, 2,632,835 B)

x86

• Code: .text +32 B (+0.0%, 198,285 B)
  No memory changes detected for:
• at32f415-start
• esp32-c3
• gd32105r-start
• hc32f334
• hpmicro-hpm5301evklite
• infineon-psoc6
• nordic-nrf51822
• nxp-lpc1114
• raspberry-pico-rp2040
• renesas-ra2l1
• stm32f407-rt-spark
• stm32l475-atk-pandora-llvm
• wch-ch32v208w-r0
• xuantie-e901plus