Verify the CMake configuration

Oct 13, 2025 by wbrum.org 102 views

Introduction

Code coverage is a crucial aspect of software development, as it helps developers understand which parts of their code are being executed during testing. However, implementing code coverage can be a manual and time-consuming process. In this article, we will explore how to use CTest's Coverage step to automate code coverage creation and collection for both Clang and GCC.

Problem Description

The implementation of code coverage is often too manual, requiring developers to build their code with specific CMake/CTest features. This can be a tedious and error-prone process, especially when working with large codebases. Moreover, the lack of automation can lead to inconsistent and incomplete code coverage reports.

Solution Description

To use CTest's Coverage step for both Clang and GCC, you need to follow these steps:

1. Enable Code Coverage Compilation Flags

To enable code coverage compilation flags, you need to modify your CMakeLists.txt file to include the following code:

include(CodeCoverage.cmake)
enable_coverage()

This will enable code coverage compilation flags for both Clang and GCC.

2. Set Up the CTest Coverage Step

To set up the CTest coverage step, you need to include the CTest module and set the CTEST_COVERAGE_COMMAND and CTEST_COVERAGE_EXTRA_FLAGS variables:

include(CTest)

if (ENABLE_COVERAGE)
    set(CTEST_COVERAGE_COMMAND "${CMAKE_CXX_COMPILER}")
    set(CTEST_COVERAGE_EXTRA_FLAGS "--coverage")
endif()

This will configure the CTest coverage step to use the C++ compiler and enable code coverage compilation flags.

3. Ensure Coverage Tools Are Available

To ensure that the coverage tools are available, you need to install the necessary packages:

For GCC (gcov):

Install gcov (should be part of your GCC package).
Install lcov if needed:

sudo apt install lcov

For Clang (llvm-cov):

Install llvm-cov:

sudo apt install llvm

Make sure llvm-cov is linked properly:

ln -s $(which llvm-cov) /usr/bin/gcov

4. Running Tests with Coverage

To run tests with coverage, you need to configure your CMake project with coverage enabled and add the necessary CTest options to the CMakePresets.json file:

{
    "version": 3,
    "binaryDir": "${sourceDir}/build",
    "buildDir": "${sourceDir}/build",
    "cacheVariables": {
        "CMAKE_BUILD_TYPE": "Debug",
        "ENABLE_COVERAGE": "ON"
    },
    "ctestArgs": {
        "CTEST_COVERAGE_COMMAND": "${CMAKE_CXX_COMPILER}",
        "CTEST_COVERAGE_EXTRA_FLAGS": "--coverage"
    }
}

5. Generating a Coverage Report

To generate a coverage report, you need to use the following commands:

For GCC (gcov and lcov):

lcov --capture --directory . --output-file coverage.info
genhtml coverage.info --output-directory coverage_report

For Clang (llvm-cov):

llvm-cov gcov --source-prefix . --object-directory . --output-file coverage.json
llvm-cov show ./your_executable -instr-profile=coverage.json > coverage_report.txt

Benefits of Using CTest's Coverage Step

Using CTest's coverage step provides several benefits, including:

Automation: CTest's coverage step automates the process of code coverage creation and collection, saving developers time and effort.
Consistency: CTest's coverage step ensures that code coverage reports are consistent and accurate, making it easier to track code coverage over time.
Flexibility: CTest's coverage step supports both Clang and GCC, making it a versatile tool for code coverage analysis.
Integration: CTest's coverage step integrates seamlessly with CMake, making it easy to incorporate code coverage into your build process.

Conclusion

In conclusion, using CTest's coverage step is a powerful way to automate code coverage creation and collection for both Clang and GCC. By following the steps outlined in this article, developers can easily integrate code coverage into their build process and generate accurate and consistent code coverage reports. Whether you're working on a small project or a large codebase, CTest's coverage step is an essential tool for any developer looking to improve their code quality and reduce bugs.

Introduction

In our previous article, we explored how to use CTest's Coverage step to automate code coverage creation and collection for both Clang and GCC. In this article, we will answer some frequently asked questions about using CTest's coverage step.

Q: What is CTest's Coverage step?

A: CTest's Coverage step is a feature of CTest that allows you to automate code coverage creation and collection for your C++ projects. It supports both Clang and GCC compilers and provides a flexible and integrated way to track code coverage.

Q: What are the benefits of using CTest's Coverage step?

A: The benefits of using CTest's Coverage step include:

Automation: CTest's coverage step automates the process of code coverage creation and collection, saving developers time and effort.
Consistency: CTest's coverage step ensures that code coverage reports are consistent and accurate, making it easier to track code coverage over time.
Flexibility: CTest's coverage step supports both Clang and GCC, making it a versatile tool for code coverage analysis.
Integration: CTest's coverage step integrates seamlessly with CMake, making it easy to incorporate code coverage into your build process.

Q: How do I enable code coverage compilation flags?

A: To enable code coverage compilation flags, you need to modify your CMakeLists.txt file to include the following code:

include(CodeCoverage.cmake)
enable_coverage()

This will enable code coverage compilation flags for both Clang and GCC.

Q: How do I set up the CTest coverage step?

A: To set up the CTest coverage step, you need to include the CTest module and set the CTEST_COVERAGE_COMMAND and CTEST_COVERAGE_EXTRA_FLAGS variables:

include(CTest)

if (ENABLE_COVERAGE)
    set(CTEST_COVERAGE_COMMAND "${CMAKE_CXX_COMPILER}")
    set(CTEST_COVERAGE_EXTRA_FLAGS "--coverage")
endif()

This will configure the CTest coverage step to use the C++ compiler and enable code coverage compilation flags.

Q: What are the system requirements for CTest's coverage step?

A: The system requirements for CTest's coverage step include:

CMake: CTest's coverage step requires CMake version 3.10 or later.
CTest: CTest's coverage step requires CTest version 3.10 or later.
Compiler: CTest's coverage step supports both Clang and GCC compilers.
Operating System: CTest's coverage step supports Linux and macOS operating systems.

Q: How do I generate a coverage report?

A: To generate a coverage report, you need to use the following commands:

For GCC (gcov and lcov):

lcov --capture --directory . --output-file coverage.info
genhtml coverage.info --output-directory coverage_report

For Clang (llvm-cov):

llvm-cov gcov --source-prefix . --object-directory . --output-file coverage.json
llvm-cov show ./your_executable -instr-profile=coverage.json > coverage_report.txt

Q: Can I use CTest's coverage step with other build systems?

A: Yes, CTest's coverage step can be used with other build systems, including Make and Ninja. However, you may need to modify the CTest configuration to accommodate the specific build system.

Q: How do I troubleshoot issues with CTest's coverage step?

A: To troubleshoot issues with CTest's coverage step, you can:

Check the CTest logs: CTest logs can provide valuable information about the coverage step, including any errors or warnings.
Verify the CMake configuration: Make sure that the CMake configuration is correct and that the coverage step is enabled.
Check the compiler flags: Make sure that the compiler flags are correct and that the coverage step is enabled.

Conclusion

In conclusion, CTest's coverage step is a powerful tool for automating code coverage creation and collection for both Clang and GCC. By following the steps outlined in this article, you can easily integrate code coverage into your build process and generate accurate and consistent code coverage reports. Whether you're working on a small project or a large codebase, CTest's coverage step is an essential tool for any developer looking to improve their code quality and reduce bugs.