Infrastructure as code is awesome, but there are too many moving parts: codebase, state file, actual cloud configuration. Things tend to drift.
Drift can have multiple causes: from developers creating or updating infrastructure through the web console without telling anyone, to uncontrolled updates on the cloud provider side. Handling infrastructure drift vs the codebase can be challenging.
You can't efficiently improve what you don't track. **We track coverage for unit tests, why not infrastructure as code coverage?**