Thin Workers, Separated Logic: The Architecture Pattern That Makes Worker Services Testable

This article addresses a critical architectural problem in .NET Worker Services: developers frequently create untestable, monolithic Worker classes by mixing orchestration logic with business logic. The solution is straightforward yet transformative—keeping the Worker thin and delegating processing to an injectable JobProcessor—which enables true unit testing without spinning up the entire host. This design principle reflects a broader industry shift toward clean separation of concerns: modular architecture with clear responsibility boundaries is essential for building scalable, maintainable backend systems.