Design for testability (unit tests, integration tests)?
Answer: Write loosely coupled code via DI. Mock external dependencies for unit tests. Use in-memory databases (e.g., InMemory EF Core) for integration tests. Isolate layers to enable focused testing.
What interviewers expect
- A clear definition tied to ASP.NET Core in ASP.NET Core projects
- Trade-offs (performance, maintainability, security, cost)
- When you would and would not use it in production
Real-world example
In a production ASP.NET Core application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.
How to explain in the interview
- Define the concept in one or two sentences.
- Context — where it fits in ASP.NET Core architecture.
- Example — a specific project, bug, or performance win.
- Trade-off — what you gain vs what you sacrifice.
Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.