Why do we need a repo-metadata.json file for testing README?
If we need info from this file, can they be mocked within the unit test itself? If it's too hard to mock within the unit tests, can we add a comment to the test to reference this file? Otherwise it is not obvious for other developers to know that the test consumes the data from this file.

The repo-metadata.json is loaded in

I think we can refactor this part so that all templates can be rendered without reading .repo-metadata.json, however, this should be a separate PR.

I'll add a comment about .repo-metadata.json.

Can we move this golden file to a different folder? Assuming .repo-metadata.json is the input of the tests, it's weird to have both input and output in the same folder. Judging by the folder name fixtures, it's probably better suited for the test set up data, not the golden files.

Done, I moved the golden file to testdata, where has all golden files associated with owlbot tests.