How to mock dependencies in unit tests

Short answer: Use a mocking framework like Moq: var mockService = new Mock<IMyService>(); mockService.Setup(s => s.Get()).Returns("test"); var controller = new MyController(mockService.Object); Mocking helps isolate the unit of work and test behavior independently. MVC & Razor Pages

Example code

Use a mocking framework like Moq: var mockService = new Mock<IMyService>();
mockService.Setup(s => s.Get()).Returns("test");
var controller = new MyController(mockService.Object); Mocking helps isolate the unit of work and test behavior independently. MVC & Razor Pages

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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.