I'm in the process of writing some new C++/WinRT based components in order to replace some much older C++/CX code. The goal is to be able to use third-party C++ tools that don't understand CX (static code analyzers, etc).
However the first step in the journey is to ensure I can properly unit test my own code. Unit testing C++/CX code typically used the "C++ Unit Test App" project type, which is C++/CX based and has its own issues (lack of code coverage support, run all required before tests show up in the explorer, stability, etc)
Browsing through the available project types in Visual Studio 2017, I did not see a unit test project template for C++/WinRT based projects. Is my only option to use the "C++ Unit Test App" template with all its failings, or is there another way to build tests for a C++/WinRT library?
Perhaps there is a way to configure either the "Native Unit Test Project" or "Google Test" project templates to support what I'm looking for?
Ideally what I'm looking for is something that doesn't require launching a UI, is pure C++(/WinRT), and supports Visual Studio's Code Coverage Analysis.
There is no unit test project that is specific to C++/WinRT, much like there isn't one for other libraries like STL. I would recommend Catch2 as it supports C++17 (a requirement for C++/WinRT) and works well on Windows. It is also what we use for testing C++/WinRT itself. Catch2 is nice because it helps you create a simple console app that acts as the test driver that includes all of the tests.
For code coverage I don't have a strong recommendation, but if you are using Visual Studio then you might want to try VSInstr. It can be used for code coverage and produces a report that can be viewed with Visual Studio.
Make sure your code is built using the /profile linker option. This will ensure that profile hooks are included in a dedicated section of the PE file. Next, run vsinstr to instrument any of the binaries you're interested in (that were previously built with /profile):
vsinstr /coverage tests.exe
Now run vsperfcmd to begin collecting coverage data:
vsperfcmd /start:coverage /output:report
Run the code as normal. For Catch2, you can simply run the executable at the command line. Then you need to stop the collection as follows:
vsperfcmd /shutdown
And you're done. You can now view the report in Visual Studio:
devenv report.coverage
Hope that helps. Again, this is not specific to C++/WinRT and since C++/WinRT is a header-only library you are liable to get a lot of noise that is unrelated to your specific project. I haven't found a good way to deal with that yet.