Definitely agree with you on that @clee , I both think unit testing is really important for mature use of the project and tests should not requrie modifying the existing DBT models.
The example I put there doesn’t really use a super-ref macro but it still requires modifying the existing ref function. Using your example of testing Model C which has depends on Source A and Model B, the testing scripts will run dbt jobs but passing it variables looking like this: {'A': 'testcase1', 'B': testcase1'}
So the ref function doesn’t guess where the test case should be but you can configure it at run time. As you I didn’t find a perfect solution that would allow fakes but I think this is good enough for testing transformations