reviewing-testability

Testability issues stem from tight coupling, side effects mixed with logic, and implicit dependencies. Review your code for dependency injection patterns, pure functions, and mock-friendly designs. This Skill analyzes your codebase to identify gaps in these areas and provides concrete refactoring steps to enforce explicit dependencies and separate side effects.

Separate presentational components from container components, accept dependencies and services as props rather than importing them directly, and keep business logic in pure functions. This pattern isolates side effects, makes mocking straightforward, and lets tests verify logic without rendering.

Dependency injection removes hard-coded dependencies, letting tests inject mock services and control behavior. Pure functions eliminate side effects, making them testable in isolation without setup or state management. Together, they reduce test complexity and increase confidence in code correctness.

Yes. This Skill reviews existing code, identifies testability gaps in dependency injection, explicit dependencies, test setup, and side-effect separation in stateful components, then provides implementable refactoring steps you can apply incrementally.

Side effects like API calls and subscriptions tangle logic with external state, making tests brittle and slow. Isolating them into pure functions and dependency-injected services lets you test logic deterministically and mock external systems reliably.

Refactoring for testability yields faster test execution, reduced mock setup overhead, higher code coverage, fewer flaky tests, and easier debugging. This Skill provides concrete, measurable testability outcomes tied to specific patterns like explicit dependencies and modularization.