godot-design_skill

Overview

This skill provides compact, practical guidelines for designing Godot GDScript interfaces that are TDD-friendly, testable, and maintainable. It codifies patterns for state queries, action signatures, signals, error handling, async operations, and test-driven design checks. The guidance is oriented toward clear, decoupled APIs and measurable test outcomes.

How this skill works

The skill inspects common Godot design decisions and recommends concrete API patterns: explicit type annotations, query methods for state assertions, well-defined signals for eventing, and error/Result-style returns. It maps those patterns to test strategies such as equivalence classes, boundary values, state-transition tests, and decision-table scenarios. Example code snippets illustrate how to structure scenes, scripts, and RefCounted utilities for easy unit and integration testing.

When to use it

• Designing new game logic classes or services in Godot
• Defining or refactoring module-to-module interfaces
• Preparing code for unit and integration tests under TDD
• Designing async resource loading and event-driven systems
• Creating reusable scene-based classes and data models

Best practices

• Always provide state query methods (getters and boolean checks) to support test assertions
• Annotate variables, function parameters, and returns with types for clarity and safety
• Use signals to decouple event notifications instead of direct callbacks
• Prefer RefCounted for pure logic/data classes and Node for scene/tree-bound behavior
• Return Error or Result-like values for failure cases and avoid hiding errors
• Design APIs with dependency injection and small, single-responsibility classes

Example use cases

• Player class exposing get_health(), is_alive(), and signals for health changes and death
• DamageCalculator or AttackCalculator implemented as RefCounted for deterministic unit tests
• AsyncLoader that emits loading_progress and loading_completed signals for integration tests
• FileLoader that returns Error or data to let tests validate error paths
• Splitting Player responsibilities into PlayerHealth, Movement, and Animation to simplify SRP-focused tests