Testing

Test time-dependent code with TimeProvider

Code that calls DateTime.UtcNow directly is hard to test. Since .NET 8, TimeProvider gives you a standard abstraction, and a fake one that you can move forward on demand.

Integration tests against a real database

The EF Core in-memory provider doesn't behave like SQL Server, so tests pass and production fails. WebApplicationFactory plus Testcontainers lets you test the real thing.