Jargon:
Virtual Service – this is a network endpoint that is a mock up of a real service, however it is simple, fast to launch, and can be setup and controlled from test automation code.
Provider – the service that is creating information
Consumer – the client that is consuming information from a Provider.
The Agile Thoughts series on the Test Automation Pyramid is a good way to learn about macro and micro testing: https://agilenoir.biz/en/agilethoughts/test-automation-pyramid-series/
These TDD episodes are a way to learn about TDD: https://agilenoir.biz/podcast/009-introducing-the-test-driven-development-series/
If you’re familiar with BDD but don’t know how to do it in SAFe, checkout this Agile Thoughts episode on BDD in SAFe: https://agilenoir.biz/en/agilethoughts/behavior-driven-development-in-full-safe-with-mike-khavkin/