Testability

Overview

This skill is about whether code can be tested cleanly, not whether tests exist.

A codebase can have many tests and still be hard to verify because the logic is trapped inside:

• route handlers
• page components
• giant service functions
• deeply stateful orchestrators
• inline conditional ladders repeated across call sites

The goal is to create code with clean seams:

• pure helpers for domain logic
• thin orchestration layers
• explicit dependencies
• narrow units that can be tested directly