Specinfra is a Ruby library that provides a common layer for infrastructure testing tools like serverspec and itamae. It offers a unified interface to check system properties (packages, services, files, network configuration, etc.) across diverse operating systems and execution environments. The architecture features a clean separation of concerns: backend abstractions for different execution methods (local, SSH, Docker, WinRM, etc.), a command factory for OS-specific command generation, and modular helpers for system detection and property management. The library dynamically selects the appropriate implementation based on the target system's OS and version, then executes checks via the chosen backend. Key entry points include the main Specinfra module, the Backend system, and the CommandFactory, which together enable extensible infrastructure verification.