doc: Generate doxygen documentation for test sources #22001

Fixes #19248

While searching for the documentation of the test utilities I realized they were excluded from doxygen. I agree with the statement in #19248. It's also helpful for new contributors to gain a broader understanding of the class dependencies visually (see BasicTestSetup)

Would you want to include all the individual tests or just the test support library? The reason for not including the test cases is to avoid clutter. I don't know how bad it would be though.

Doxygen is doing a decent job grouping files together by macro. See the following screenshots as an example for the Fuzz and Boost tests

I think adding the individual tests is even beneficial as it gives you a quick overview of what is currently being covered by the test frameworks and allows you to drill down into the tests and dependencies.

The generation takes obviously slightly longer. In total we end up with 6557 more files while 5985 are purely graphs. Not sure if that's a concern from a CI and hosting perspective though. Are the doxygen docs getting generated for the master branch by CI and hosted somewhere?

Thanks for checking. I agree, If it doesn't seem to add confusion for people browsing the documentation then covering everything (except subtrees) is preferable.

Are the doxygen docs getting generated for the master branch by CI and hosted somewhere?

Yes :smile: https://doxygen.bitcoincore.org This runs on one of my servers, it's only regenerated once every day so having it take up a bit more time/space isn't a big deal.

Concept ACK

ACK 5d37cc44f9200861a278d074f8caa99e8db6be02