What tools or libraries help you enforce SOLID principles in .NET code?

Short answer: Resharper: Provides code analysis and refactoring hints. SonarQube / SonarCloud: Analyzes code quality and reports SOLID violations. FxCop / Roslyn analyzers: Provide static analysis with custom rules. NDepend: Deep architecture and dependency analysis tool. StyleCop: Enforces coding style which indirectly helps maintain SOLID code.

Real-world example (ShopNest)

Open/Closed in ShopNest: add a new payment method by adding a class, not by editing a giant switch in CheckoutService.

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.