Embedded Testing

When to activate

• Setting up unit testing for firmware (Unity, Ceedling, Google Test)
• Designing hardware-in-the-loop (HIL) test systems
• Building CI/CD pipelines for embedded projects
• Implementing mock strategies for hardware dependencies
• Creating automated regression test suites

When NOT to use

• For production testing methodology (SPC, Six Sigma)
• For hardware validation and certification testing
• For manual exploratory testing

Instructions

1. Unit testing. Unity (C) or Google Test (C++) for logic tests. Mock HAL functions. Test drivers with fake I2C/SPI.
2. Test structure. tests/unit/ for isolated logic, tests/integration/ for multi-module, tests/system/ for full firmware on target.
3. Mock strategy. Stub HAL functions. Fake sensor returns. Simulate network responses. Use FFF (Fake Function Framework) for C.
4. HIL testing. Real hardware + test harness. Automated via Python/serial commands. Test real timing, real peripherals.
5. CI/CD pipeline. Build (cross-compile) → Static analysis (cppcheck, clang-tidy) → Unit tests → Flash to test board → HIL tests.
6. Coverage. gcov for code coverage. Target >80% for critical modules (safety, communication). Use branch coverage for state machines.
7. Test documentation. Test plan with cases. Traceability: requirement → test case → result. Regression suite grows with each bug fix.

Example

# CI Pipeline for Embedded Firmware
steps:
  - name: Build
    run: arm-none-eabi-gcc -O2 -Wall -Werror src/*.c
    
  - name: Static Analysis
    run: cppcheck --enable=all --error-exitcode=1 src/
    
  - name: Unit Tests
    run: |
      cd tests/unit
      make test
      gcov --branches src/*.c
      
  - name: Flash & HIL
    run: |
      openocd -f interface/stlink.cfg -c "program build/firmware.elf"
      python tests/hil/run_hil.py --serial /dev/ttyUSB0
      
  - name: Coverage Report
    run: genhtml coverage/*.gcov --output-directory coverage_html