PluginPublic

testland/googletest-embedded-arm

Use when embedded C++ (C++17 or later) on ARM needs unit tests with GoogleTest: TEST, TEST_F and parameterized tests, EXPECT vs ASSERT, fixtures, GoogleMock, cross-compiling with arm-none-eabi-g++, running on host or QEMU and XML output for CI. Pure C uses unity-test-framework-c.

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GoogleTest cross-compile, output parsing, and CI for embedded ARM

Deep reference for the googletest-embedded-arm SKILL.md. Consult when wiring the full toolchain (host CMake, Cortex-M / Cortex-A cross-compile), reading the XML / JSON output schema, or gating CI.

Host build (fast inner loop)

CMake:

include(FetchContent)
FetchContent_Declare(googletest
    GIT_REPOSITORY https://github.com/google/googletest.git
    GIT_TAG v1.17.0)
FetchContent_MakeAvailable(googletest)

add_executable(ringbuffer_test test/ringbuffer_test.cpp)
target_link_libraries(ringbuffer_test PRIVATE gtest_main)
enable_testing()
add_test(NAME ringbuffer_test COMMAND ringbuffer_test)

gtest_main provides a main() that calls testing::InitGoogleTest(&argc, argv) then RUN_ALL_TESTS() - which "returns 0 on success, 1 on failure" and per google.github.io/googletest/primer.html "You must not ignore the return value of RUN_ALL_TESTS()".

Cortex-M cross-compile (under QEMU)

The standard recipe - uses arm-none-eabi-g++ for the toolchain, --specs=rdimon.specs to pull in the librdimon semihosting library so stdout reaches QEMU:

arm-none-eabi-g++ -mcpu=cortex-m4 -mthumb -mfpu=fpv4-sp-d16 -mfloat-abi=hard \
    -O0 -g -std=c++17 \
    -DGTEST_HAS_PTHREAD=0 -DGTEST_OS_LINUX=0 -DGTEST_LANG_CXX11=1 \
    --specs=rdimon.specs \
    -I/path/to/googletest/googletest/include \
    test/ringbuffer_test.cpp /path/to/googletest/googletest/src/gtest-all.cc \
    -o ringbuffer_test.elf -lrdimon

-DGTEST_HAS_PTHREAD=0 is critical - bare-metal targets have no pthreads; the build fails without it. (The flag is documented in GoogleTest's port.h.) For Cortex-A Linux targets, use the standard arm-linux-gnueabihf-g++ and drop the --specs flag.

Build invariants

Invariant	Why
`-O0 -g` for coverage builds	gcov / llvm-cov measure post-optimisation flow; see `embedded-coverage-strategy-reference`
`-Wno-psabi` on ARM	Suppresses noisy ABI warnings on cross-compile
`-fno-exceptions -fno-rtti` if MCU build does	Match the production firmware's flags so virtual dispatch matches
Link with `-Wl,--gc-sections` + compile with `-ffunction-sections -fdata-sections`	Keeps the .elf small enough for low-RAM Cortex-M0 simulation

Command-line flags (full set)

Per the Advanced Guide:

Flag	Effect
`--gtest_filter=Pattern`	"a `:`-separated list of wildcard patterns" - supports `*`, `?`, and negative `-` patterns
`--gtest_repeat=N`	Repeats all tests N times (use `-1` for infinite - useful for flake hunting)
`--gtest_shuffle`	Random order each run - "reveal bad dependencies between tests"
`--gtest_output=xml:results.xml` / `json:results.json`	Machine-readable report (the value is `"xml:path"` or `"json:path"`)
`--gtest_break_on_failure`	Drops into debugger on first failure
`--gtest_catch_exceptions=0`	Disables exception handling - lets debugger catch the throw
`--gtest_color=yes\|no\|auto`	Coloured terminal output
`--gtest_brief=1`	Only failures shown
`--gtest_list_tests`	List without running

Parsing results

XML output schema

Per the Advanced Guide, the XML follows a hierarchical structure with <testsuites> / <testsuite> / <testcase> elements, with <failure> nodes nested under failing <testcase> entries:

<?xml version="1.0" encoding="UTF-8"?>
<testsuites tests="7" failures="1" time="0.012">
  <testsuite name="RingbufferTest" tests="2" failures="0" time="0.001">
    <testcase name="EmptyOnInit" status="run" time="0.000"/>
    <testcase name="PushIncrementsSize" status="run" time="0.001"/>
  </testsuite>
  <testsuite name="WrapTest" tests="5" failures="1" time="0.011">
    <testcase name="WrapAtCapacity/4" status="run" time="0.002">
      <failure message="Expected: 5, actual: 4"/>
    </testcase>
  </testsuite>
</testsuites>

JUnit-compatible - feeds straight into GitHub Actions actions/upload-artifact + mikepenz/action-junit-report.

JSON output schema

Per the Advanced Guide: a "Proto3-compatible structure with UnitTest -> TestCase -> TestInfo -> Failure hierarchy, including timestamps and durations". Prefer JSON for custom dashboards; XML for the JUnit ecosystem.

Parsing pattern

./ringbuffer_test --gtest_output=xml:results.xml
xmlstarlet sel -t -v "count(//testcase[failure])" results.xml
# Number of failing testcases - gate on this

CI integration

jobs:
  embedded-tests:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v5
      - name: Install ARM toolchain
        run: sudo apt-get install -y gcc-arm-none-eabi qemu-system-arm
      - name: Configure (host build)
        run: cmake -S . -B build-host -DCMAKE_BUILD_TYPE=Coverage
      - name: Build + run on host
        run: |
          cmake --build build-host
          ./build-host/ringbuffer_test \
            --gtest_output=xml:build-host/host-results.xml \
            --gtest_shuffle
      - name: Cross-compile + run under QEMU
        run: |
          arm-none-eabi-g++ -mcpu=cortex-m4 -mthumb -O0 -g -std=c++17 \
            -DGTEST_HAS_PTHREAD=0 --specs=rdimon.specs \
            -I ext/googletest/googletest/include \
            test/ringbuffer_test.cpp ext/googletest/googletest/src/gtest-all.cc \
            -o build-arm/ringbuffer_test.elf -lrdimon
          qemu-system-arm -M mps2-an385 -cpu cortex-m4 \
            -nographic -semihosting-config enable=on,target=native \
            -kernel build-arm/ringbuffer_test.elf
      - name: Publish JUnit
        uses: mikepenz/action-junit-report@v4
        with:
          report_paths: 'build-host/*-results.xml'

The host build gates on the JUnit XML; the QEMU build gates on QEMU's exit code (semihosting exit(RUN_ALL_TESTS()) propagates the gtest return value through QEMU).

.tessl-plugin

references

authoring-variants.md

cross-compile-and-ci.md

SKILL.md

tile.json