How Do I Generate Test Coverage Reports for Unit Tests in STM32CubeIDE

STM32CubeIDE is a powerful and versatile development environment tailored for embedded systems programming with STM32 microcontrollers. While it offers extensive debugging features, generating test coverage reports for unit tests is not directly available. However, you can generate meaningful test coverage reports for your projects by enabling the correct compiler options and using external tools.

What is Test Coverage?

Test coverage measures how much of the source code is executed during testing. It helps developers identify untested parts of their codebase, ensuring more comprehensive and robust testing. Generating coverage reports can guide the development of additional test cases and improve software reliability.

Steps to Generate Test Coverage Reports

1. Enable Code Instrumentation in STM32CubeIDE

   To collect coverage data, the code needs to be instrumented during compilation.

   • Open your project in STM32CubeIDE.
   • Navigate toProject Properties > C/C++ Build > Settings.
   • UnderMCU GCC Compiler > Miscellaneous, ensure you add appropriate flags to enable code instrumentation for coverage analysis.
   • Go toMCU GCC Linker > Miscellaneous, and configure the settings to support the generation of coverage data.

   These options ensure the compiler generates the necessary data files during test execution.

2. Write Unit Tests for Your C++ Code

   Below is a simple example of a C++ function and its corresponding unit test:

   cpp
   #include <iostream>
   #include <cassert>
   // Function to be tested
   int add(int a, int b) {
   return a + b;
   }
   int main() {
   // Unit test for the add function
   int result = add(2, 3);
   assert(result == 5); // Test passes if result is 5
   std::cout << "Test Passed: Result is " << result << std::endl;
   return 0;
   }
   
   
   This simple test checks whether the `add` function correctly returns the sum of two integers.
   

3. Build and Run the Unit Tests

   Compile and run your project in STM32CubeIDE as usual. When the program executes, the compiler will generate coverage data files, which can be used for analysis.

4. Generate Coverage Reports Using Gcov

   After running the tests, open a terminal and navigate to the project directory containing the source files. Execute the necessary commands to generate coverage reports. This will create files that include coverage information, such as which lines of code were executed and which were missed.

5. Visualize Coverage Reports

   To visualize the coverage results, you can use additional tools like gcovr or lcov.

   - Install gcovr:
   sh
   pip install gcovr
   
   
   - Generate an HTML report:
   sh
   gcovr -r . --html --html-details -o coverage_report.html
   Open the `coverage_report.html` file in your browser to see a detailed and interactive report.
   

Conclusion

By enabling the correct compiler flags and leveraging tools like Gcov and Gcovr, you can generate comprehensive test coverage reports for your unit tests in STM32CubeIDE. This setup helps ensure better code quality and more reliable embedded systems.