Are there any formal tests or exams?

No tests, no exams. Progress here is visible in what you can build, not in what you can recall on a timed quiz. If you can solve the problem, structure the project, explain your decisions, and hand something off to another person who understands it — you’ve learned it. That’s the only test that matters. Occasionally someone really wants to be tested on something specific, and when that happens we’ll put something together. But the default is: the work itself is the assessment.