用 Twister 与 pytest 自动验证 Zephyr Shell

Zephyr 的这个示例展示了如何让 Twister 负责发现、构建和汇总测试,再让 pytest 向应用的 Shell 发送命令并检查返回内容。测试只有两项:help 是否返回预期的命令列表标记,以及 kernel version 是否返回 Zephyr 版本信息。

本文按 Zephyr 4.4.0 的 Pytest shell application testing 整理,并核对了官方仓库 v4.4.0 标签下的 README、应用源码、Kconfig 配置、测试配置和 Python 测试文件。固定版本网页本次未能通过读取工具打开,已用对应版本的官方源文件完成全文核验。下列日志来自原文,本文没有安装、构建、烧录或运行该示例。

Twister 读取测试配置并构建 Zephyr Shell 应用,调用 pytest 子进程;shell 夹具发送 help 与 kernel version,pytest 输出 results.xml,Twister读取报告判定结果。
Twister、pytest 和 Zephyr Shell 的职责及报告流向。未完纪自绘示意图,非测试截图。

运行条件与版本边界

示例需要具有 UART 控制台的目标平台,可以是硬件开发板、native_sim 或 QEMU。4.4.0 的测试配置还要求启用串口、没有启用 SMP,并且设备树中 zephyr,shell-uart 所指节点有效。配置列出的集成平台为 native_sim 与 qemu_cortex_m3,并排除 qemu_rx。这些条件都应保留,不应因为“支持 pytest”就推断所有平台都能运行。

配套的 pytest 集成说明 仍把这项集成标记为进行中的工作。默认无需另外安装一个浮动版本的 pytest-twister-harness:Twister 会把源码树内插件的路径加入 PYTHONPATH,再用 -p twister_harness.plugin 加载它。只有明确使用已安装插件时才涉及 --allow-installed-plugin;本文使用源码树随附插件。

对于 native_sim,默认目标使用 32 位 ILP32 ABI,指针和 long 均为 32 位。在 64 位主机上通常需要相应的 multilib 支持,或使用 32 位用户空间。native_sim/native/64 使用 LP64 ABI,指针和 long 为 64 位;它可以解决部分主机不能运行 32 位程序的问题,但改变了 ABI,不能被当作完全等价的测试目标。

应用为什么可以没有业务逻辑

目录 samples/subsys/testsuite/pytest/shell 包含应用与测试。src/main.c 的作用很小,因为 Shell 功能由 Kconfig 选项引入。以下为原文件代码,注释保留其原始拼写:

/*
 * Copyright (c) 2023 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: Apache-2.0
 */

int main(void)
{
    /* Shell application source code is injected by applied Kconfg SHELL
     * options, no more "extra" functionalities are required for exemplary
     * pytest test.
     */
    return 0;
}

prj.conf 的完整配置为:

CONFIG_PRINTK=y
CONFIG_SHELL=y
CONFIG_LOG=y
CONFIG_SHELL_BACKEND_SERIAL=y
CONFIG_KERNEL_SHELL=y

CONFIG_SHELL 启用 Shell,串口后端提供交互通道,CONFIG_KERNEL_SHELL 提供测试所用的内核命令。因此,不需要在 main() 里自行实现 help 或 kernel version。

两条测试分别验证什么

Twister 构建应用后,会调用 pytest 子进程运行 pytest/test_shell.py。两项测试都接收由 pytest-twister-harness 提供的 shell 夹具。下面保留该文件的完整逻辑及版权声明:

# Copyright (c) 2023 Nordic Semiconductor ASA
#
# SPDX-License-Identifier: Apache-2.0

import logging

from twister_harness import Shell

logger = logging.getLogger(__name__)


def test_shell_print_help(shell: Shell):
    logger.info('send "help" command')
    lines = shell.exec_command('help')
    assert 'Available commands:' in lines, 'expected response not found'
    logger.info('response is valid')

def test_shell_print_version(shell: Shell):
    logger.info('send "kernel version" command')
    lines = shell.exec_command('kernel version')
    assert any(['Zephyr version' in line for line in lines]), 'expected response not found'
    logger.info('response is valid')

第一条断言检查返回的行集合中是否包含完整的一行 Available commands:;它不是在验证每一个命令及其说明。第二条断言检查是否至少有一行包含 Zephyr version;它也不要求某个固定版本号。因此,这两项测试验证的是基本 Shell 交互和输出格式,没有覆盖所有 Shell 功能、设备安全性或版本一致性。

理解 testcase.yaml 的平台筛选与变体

4.4.0 的完整配置如下。保留整个文件有助于解释为什么仅指定测试目录可能选中不止本篇的两项断言:

common:
  tags:
    - test_framework
    - pytest
    - shell
  platform_exclude: qemu_rx
  filter: CONFIG_SERIAL and not CONFIG_SMP and dt_chosen_enabled("zephyr,shell-uart")
  extra_configs:
    - arch:posix:CONFIG_UART_NATIVE_PTY_0_ON_STDINOUT=y
    - platform:iotdk/arc_iot:CONFIG_ARC_IOT_CUSTOM_CPU_IDLE=y
  min_ram: 40
  integration_platforms:
    - native_sim
    - qemu_cortex_m3
tests:
  sample.pytest.shell:
    harness: pytest
  sample.pytest.shell.vt100_colors_off:
    harness: pytest
    extra_configs:
      - CONFIG_SHELL_VT100_COLORS=n
  sample.harness.shell:
    harness: shell
    harness_config:
      shell_commands: &kernel_commands
        - command: "kernel cycles"
          expected: "cycles: .* hw cycles"
        - command: "kernel version"
          expected: "Zephyr version .*"
        - command: "kernel sleep 100"
  sample.harness.shell.vt100_colors_off:
    harness: shell
    extra_configs:
      - CONFIG_SHELL_VT100_COLORS=n
    harness_config:
      shell_commands: *kernel_commands
  sample.pytest.required_app_demo:
    required_applications:
      - name: sample.pytest.shell
      - name: sample.harness.shell
    harness: pytest
    harness_config:
      pytest_root:
        - "pytest_shared_app/test_shared_app.py"

sample.pytest.shell 是本文主场景;带 vt100_colors_off 的 pytest 场景关闭终端颜色。sample.harness.shell 使用不同的 Shell harness,命令包括 kernel cycles、kernel version 和 kernel sleep 100。共享应用示例依赖两个已构建应用,并把测试入口改为 pytest_shared_app/test_shared_app.py。这些变体存在于同一 YAML 中,但其结果不能替代本文两条 Python 断言的结果。

构建与运行:限定本篇场景

原 README 给出的命令如下,应在已完成环境准备的 Zephyr 源码根目录运行:

./scripts/twister -vv --platform native_sim -T samples/subsys/testsuite/pytest/shell

本文整理后的命令:在原命令后增加 -s sample.pytest.shell,只选择本文讨论的场景。这是相对于原 README 的明确改动:

./scripts/twister -vv --platform native_sim   -T samples/subsys/testsuite/pytest/shell   -s sample.pytest.shell

-T 限制发现测试的目录,--platform 选择目标,-vv 提高日志详细程度,-s 选择场景。命令会构建并运行应用;它不是只读检查。本文没有把真实硬件烧录或擦除选项加入这一命令。

怎样阅读原文的示例日志

下面保留原 README 展示的输出内容。首尾省略号本来就存在于原文,表示这不是一次完整运行的日志。版本 3.5.99 是历史示例输出,不是 Zephyr 4.4.0 的期望版本,也不是本文运行得到的结果:

...
samples/subsys/testsuite/pytest/shell/pytest/test_shell.py::test_shell_print_help
INFO: send "help" command
DEBUG: #: uart:~$ help
DEBUG: #: Please press the <Tab> button to see all available commands.
DEBUG: #: You can also use the <Tab> button to prompt or auto-complete all commands or its subcommands.
DEBUG: #: You can try to call commands with <-h> or <--help> parameter for more information.
DEBUG: #: Shell supports following meta-keys:
DEBUG: #: Ctrl + (a key from: abcdefklnpuw)
DEBUG: #: Alt  + (a key from: bf)
DEBUG: #: Please refer to shell documentation for more details.
DEBUG: #: Available commands:
DEBUG: #: clear    :Clear screen.
DEBUG: #: device   :Device commands
DEBUG: #: devmem   :Read/write physical memory
DEBUG: #:             Usage:
DEBUG: #:             Read memory at address with optional width:
DEBUG: #:             devmem address [width]
DEBUG: #:             Write memory at address with mandatory width and value:
DEBUG: #:             devmem address <width> <value>
DEBUG: #: help     :Prints the help message.
DEBUG: #: history  :Command history.
DEBUG: #: kernel   :Kernel commands
DEBUG: #: rem      :Ignore lines beginning with 'rem '
DEBUG: #: resize   :Console gets terminal screen size or assumes default in case the
DEBUG: #:             readout fails. It must be executed after each terminal width change
DEBUG: #:             to ensure correct text display.
DEBUG: #: retval   :Print return value of most recent command
DEBUG: #: shell    :Useful, not Unix-like shell commands.
DEBUG: #: uart:~$
INFO: response is valid
PASSED
samples/subsys/testsuite/pytest/shell/pytest/test_shell.py::test_shell_print_version
INFO: send "kernel version" command
DEBUG: #: uart:~$ kernel version
DEBUG: #: Zephyr version 3.5.99
DEBUG: #: uart:~$
INFO: response is valid
PASSED
...

帮助信息解释了 Tab 补全、-h/--help、快捷键以及可用命令。日志里列出的 devmem 具备物理内存读写能力;它只是历史帮助文本的一部分,本篇测试没有调用它,也不应把该输出当成开放调试 Shell 给不受信任使用者的安全依据。

实际验收应检查本次所选场景的两条断言及 pytest 报告。Twister 把构建目录、设备等参数通过 YAML 配置传给 pytest;pytest 结束后,Twister 读取 results.xml 并据此设置结果。看到旧日志里的 PASSED 不等于本机运行成功,构建成功也不等于两条断言通过。

静态审查与归属

本次只做安全静态审核。源测试发送的是固定的 help 和 kernel version 字符串,没有硬编码秘密或外部输入拼接执行;不过 Shell 接口本身可能提供高权限调试命令,生产固件需另行审阅暴露范围。没有执行任何源代码、测试、烧录或网络配置,未发现问题不代表不存在漏洞。

原文维护方为 Zephyr Project,页面未列个人作者;所引 main.c 和 test_shell.py 保留 Copyright (c) 2023 Nordic Semiconductor ASA 及 SPDX-License-Identifier: Apache-2.0。代码适用 Apache License 2.0,文末附完整许可。中文译写、自绘图和限定场景的命令说明由未完纪整理。

核对来源:示例 README、Python 测试、测试配置。所有版本相关解释均限定在已核对的 v4.4.0 源文件。

Zephyr 示例代码 Apache License 2.0 全文

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