What should I test first with Android Clean Architecture (TDD)

I'm learning TDD with my toy project with Android Clean Architecture.

I want to know how to process my Unit Test.

I want to do TDD with my search features, in this case, Should I create my UseCase and test it first?

Or should create api client and test it first with fake data?

If my question is not understandable, please notice me.

Thanks for your answer.

With a Clean Architecture I would always start with the UseCases first, because this is where your business logic and therefore the value is. Anything related to implementing Adapters can be defered to the latest possible time.