dotnet-development

CIEL ADAPTATION: .NET Development (Modern & Typed)

This skill formalizes the development of robust C# applications using .NET 8+. it prioritizes immutability, explicit DI, and async efficiency.

Idiomatic Standards

1. Immutability First: Use public sealed record for all DTOs and Value Objects. Use init setters for optional properties.
2. Explicit Nullability: Enable <Nullable>enable</Nullable>. Use ? for optional types.
3. Async Efficiency: Use await all the way down. ALWAYS pass CancellationToken to async I/O calls.
4. DI Discipline: Depend on abstractions (IInterface). Prohibit manual new Service() in business logic.

ASP.NET Core Patterns

• Minimal APIs: Use MapGroup to organize routes. Use TypedResults for unit-testable responses.
• Options Pattern: Map config sections to sealed class options. Inject via IOptions<T>.
• Middleware: Use for cross-cutting concerns (Logging, Auth, Performance).

TDD & Verification

• Framework: xUnit + FluentAssertions.
• Mocking: Use NSubstitute for clean, interface-based mocking.
• Integration: Use WebApplicationFactory and Testcontainers for real infrastructure testing (SQL, Redis).
• Gate: Run dotnet test with 80% coverage check.

Anti-Patterns

• Async Void: Using async void except for top-level event handlers.
• Blocking on Async: Using .Result or .Wait() (causes deadlocks).
• Fat Controllers: Putting business logic in API controllers instead of Services or MediatR handlers.