.NET architecture tests - fitness functions

The architecture-decision skill decides what the structure should be (clean, vertical-slice, DDD, modular, microservices); this skill makes a test prove it, and fail the build the moment a boundary is crossed. Without that, a layering rule lives only in a diagram and a reviewer's memory, so it erodes silently - one stray using at a time - until the next big refactor. It is the enforcement counterpart to those concept skills - the same relationship the .NET code-quality skill has to the C# style rules. Baseline is .NET 8 / C# 12.

When to use

• Also fires on: fitness function, architecture test, dependency rule.
• .NET conventions for architecture fitness tests - encoding layer/dependency/naming/isolation rules as tests that fail the build on a violation, so the structure the architecture-decision skill prescribes cannot erode silently.
• Do NOT load for runtime behavior tests or analyzer / formatter config - the .NET testing and code-quality skills own those.

Pick the library: NetArchTest by default

Default to NetArchTest.Rules: lightweight, fluent, fast, and zero-ceremony - assertions over namespaces, dependencies, and layering that read cleanly in a normal test.