Production checklist

Shipping .NET means nullable warnings as errors, analyzers, pinned SDKs, structured logging, and tests in CI—not just "it runs on my machine."

Checklist

• <Nullable>enable</Nullable> and treat warnings seriously
• dotnet format and Roslyn analyzers in CI
• Pin SDK with global.json; lock package versions
• Use ILogger instead of Console.WriteLine in services
• Unit tests with dotnet test; integration tests for databases separately
• Profile before micro-optimizing LINQ or allocations
• Web concerns (auth, EF, deployment) live in the ASP.NET track

Important interview questions and answers

1. Q: Why enable nullable reference types?
   A: Surfaces null contracts at compile time—reduces NullReferenceException defects in large codebases.
2. Q: How reduce GC pressure?
   A: Avoid unnecessary allocations in hot paths, pool buffers when profiling proves need, prefer structs for tiny immutable data.

Self-check

1. What file pins the SDK version?
2. Why separate unit and integration tests?
3. Name the CLI command that runs tests.

Track summary

You covered C# language fundamentals, OOP, collections, LINQ, modern features, CLR tooling, and interview context. Continue with local dotnet new projects and explore the ASP.NET track for web APIs or Unity Hub for game scripting with C#.

Next steps

1. Build a class library + console app solution locally
2. Practice LINQ and async on exercism.org or Advent of Code in C#
3. Compare patterns with Java, Python, and C++ tracks
4. Advance to ASP.NET for HTTP, MVC, and EF Core

Tip: Treat nullable warnings as errors in CI once the codebase is clean—<Nullable>enable</Nullable> pays off at scale. This lesson also closes the track—next stop: ASP.NET.