Don’t Discard Test-Driven Development in the Cloud
No matter which option you choose, keep in mind that these are methods for functional unit testing of your code. Load testing and scaling exercises are a different matter and likely will require you set up large server (or virtual server) clusters that mimic your production environment.
That sort of testing is outside the scope of most TDD, which is focused more on functional unit testing. Keep your TDD focused on validating features and covering code with tests before you refactor it.
Due to the rapid changes in cloud computing and the open source nature of these projects, you may find the lack of documentation, examples, and completed libraries frustrating. Just keep in mind that you are on the bleeding edge of software development, and be proud of that. You definitely should not let those factors become an excuse not to keep up with good development practices like TDD.