Generate run_results.json even when no nodes are selected

[panasenco]

Describe the feature

I'd like the file target/run_results.json to be generated with an empty results list even when the selector selected no nodes. The current behavior is to not generate a new run_results.json when the selector returned no nodes.

A test run with no nodes selected is a legitimate occurence when using the state:modified selector.

Describe alternatives you've considered

Parsing dbt test output for the string WARNING: Nothing to do. Try checking your model configs and model specification args. This is a bit hacky and unreliable though.

Additional context

Using dbt test with the state:modified selector in my CI pipeline. I parse run_results,json to get the test outcome, but that file doesn't get generated when there are no model differences between the branch and PROD. However, the absence of run_results.json could also mean the test process somehow failed...

Who will this benefit?

Anyone who depends on run_results.json - for example CI pipeline devs.

Are you interested in contributing this feature?

I'll browse the source code and give it a shot, but no promises.

[jtcohen6]

@panasenco I buy it! Thanks so much for opening the issue, and for laying out your rationale so clearly. It looks like this was a super simple change, too.