What are the limitations of mocking?

Short answer: Cannot mock non-virtual or sealed methods/classes without special tooling. Over-mocking can make tests fragile and hard to maintain. Complex mocks can hide design issues in the code. Mocks don’t guarantee real-world integration correctness.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.