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Table of contents

  1. Important functions
  2. Out of source builds
  3. Running tests
  4. Test code coverage reports
  5. Suggested reading

Important functions

You will need to modify parts of CMakeLists.txt to work for your project. You should familiarize yourself with the following important functions:

  • add_library (doc)
    • Defines a library with the specified source files.
  • add_executable (doc)
    • Defines an executable with the specified source files.
  • target_link_libraries (doc)
    • Defines library dependencies for executables. Used to link executables to libraries. In addition to your defined libraries, you may need to link with:
      • Boost::log
      • Boost::signals
      • Boost::system
      • gtest_main
      • Threads::Threads
  • gtest_discover_tests (doc)
    • Defines tests for the given gtest test executable.
  • add_test (doc)
    • Defines a manual test with a given command. Useful for non-gtest non-C++ tests (like integration test scripts).
  • generate_coverage_report
    • Creates a code coverage report. See CodeCoverageReportConfig.cmake source for documentation.

Out of source builds

CMake generates numerous output files, even before performing a build. In order to keep all of CMake’s output isolated, you should perform out-of-source builds. In short, this means creating a build directory, and running cmake from that directory, referencing the directory containing CMakeLists.txt (usually the parent directory):

$ mkdir build
$ cd build
$ cmake ..
$ make

If you need to clean out all the generated build files, you can simply delete the build directory and start over. Additionally, if you want to run cmake with multiple configurations (e.g. different sets of -D defines), then you can create multiple build directories (or sub-directories) from which you can run different cmake configurations.

Running tests

CMake includes the ctest program that allows you to build and run tests (assuming cmake has already been run). CMake also creates a test target in the generated Makefile that wraps ctest:

$ ctest


$ make test

To see more test output, run ctest with the -V flag:

$ ctest -V


$ make test ARGS=-V

Test code coverage reports

The project templates include a CMake macro for generating code coverage reports with gcovr. A code coverage build of a binary includes extra code to generate output files showing which lines and branches were executed. To avoid interference with your regular build, perform an out-of-source build in a different directory (e.g. build_coverage instead of build). For example, to generate code coverage reports for the CMakeLists.txt generated from our project templates:

$ mkdir build_coverage
$ cd build_coverage
$ cmake -DCMAKE_BUILD_TYPE=Coverage ..
$ make coverage

This will create an HTML report in ${REPO}/build_coverage/report/index.html that you can view in your browser.

Suggested reading

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Page last modified: May 30, 2022.