Your question is Test a Submarine With Limited Software. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
How do we test our submarine with only this much software
Explain how you would build confidence in software that interacts with sensors, vehicle controls, communications, and safety-critical state transitions when access to the real submarine is limited. Cover test doubles, simulation, hardware-in-the-loop testing, fault injection, offline analysis, deployment gates, and how you would detect failures that the test environment does not reproduce.