91
What are the SOLID principles?
SOLID is a group of five object-oriented design principles intended to improve maintainability, flexibility, and testability.
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SOLID, DI, Testing & Practical C#
C# interview questions covering solid, di, testing & practical c#.
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92
What is the Single Responsibility Principle?
The Single Responsibility Principle states that a class or module should have one focused responsibility or one primary reason to change.
93
What is dependency injection in C# and ASP.NET Core?
Dependency Injection (DI) is a design technique where a class receives its dependencies from outside rather than creating them internally.
94
What is the difference between Transient, Scoped, and Singleton lifetimes?
ASP.NET Core's DI container supports several service lifetimes.
95
What is loose coupling, and why is it important?
Loose coupling means components depend as little as practical on concrete implementation details.
96
What is unit testing in C#?
Unit testing verifies a small unit of behavior, such as a method or service, in isolation from unrelated infrastructure.
97
What is mocking in unit testing?
Mocking replaces a dependency with a controllable test double so that the unit under test can be tested without calling the real external component.
98
What is the difference between unit testing and integration testing?
Unit testing focuses on a small piece of logic and normally isolates external dependencies. It is fast and useful for verifying business rules and edge cases.
99
What are common C# performance best practices?
Performance optimization should be driven by measurement rather than assumptions. Profiling, tracing, metrics, database execution plans, and benchmarks help identify actual bottlenecks.
100
How would you design clean and maintainable C# code for a production application?
Clean production C# code should have clear responsibilities, meaningful names, appropriate abstractions, predictable error handling, and strong testability.