Integrating googletest in CMake-based projects and Jenkins

In my – admittedly limited – perception unit testing in C++ projects does not seem as widespread as in Java or the dynamic languages like Ruby or Python. Therefore I would like to show how easy it can be to integrate unit testing in a CMake-based project and a continuous integration (CI) server. I will briefly cover why we picked googletest, adding unit testing to the build process and publishing the results.

Why we chose googletest

There are a plethora of unit testing frameworks for C++ making it difficult to choose the right one for your needs. Here are our reasons for googletest:

• Easy publishing of result because of JUnit-compatible XML output. Many other frameworks need either a Jenkins-plugin or a XSLT-script to make that work.
• Moderate compiler requirements and cross-platform support. This rules out xUnit++ and to a certain degree boost.test because they need quite modern compilers.
• Easy to use and integrate. Since our projects use CMake as a build system googletest really shines here. CppUnit fails because of its verbose syntax and manual test registration.
• No external dependencies. It is recommended to put googletest into your source tree and build it together with your project. This kind of self-containment is really what we love. With many of the other frameworks it is not as easy, CxxTest even requiring a Perl interpreter.

Integrating googletest into CMake project

1. Putting googletest into your source tree
2. Adding googletest to your toplevel CMakeLists.txt to build it as part of your project:

   add_subdirectory(gtest-1.7.0)

3. Adding the directory with your (future) tests to your toplevel CMakeLists.txt:

   add_subdirectory(test)

4. Creating a CMakeLists.txt for the test executables:

   include_directories(${gtest_SOURCE_DIR}/include)
   set(test_sources
   # files containing the actual tests
   )
   add_executable(sample_tests ${test_sources})
   target_link_libraries(sample_tests gtest_main)
   

5. Implementing the actual tests like so (@see examples):

   #include "gtest/gtest.h"
   
   TEST(SampleTest, AssertionTrue) {
       ASSERT_EQ(1, 1);
   }
   

Integrating test execution and result publishing in Jenkins

1. Additional build step with shell execution containing something like:

   cd build_dir && test/sample_tests --gtest_output="xml:testresults.xml"

2. Activate “Publish JUnit test results” post-build action.

Conclusion

The setup of a unit testing environment for a C++ project is easier than many developers think. Using CMake, googletest and Jenkins makes it very similar to unit testing in Java projects.