The test are in the core module so that they can be executed for all the dialects. There is a bit of magic involved.
You can run them using maven via

mvn install -pl mongodb -am

Or you can copy them in the MongoDB module and launch them using the IDE.

I copied the classes in your project involved with the issue. I couldn't test your project directly because it was too complex as a test case and I'm not overly familiar with IDEA.

I will try later to create an integration test with WilfFly to double check.