What problem does it solve? Writing unit tests for Vue 3 applications that use Pinia often leads to brittle, implementation-coupled tests or incorrect store mocking. This Skill provides a structured workflow and canonical patterns for testing components, composables, and stores with Vitest, Vue Test Utils, and createTestingPinia, keeping tests behavior-first and deterministic. ## Core Features & Use Cases - Pinia Test Setup Guidance: Standard patterns for createTestingPinia, including action spying with createSpy, state seeding with initialState, executing real actions with stubActions, and getter overrides. - Behavior-First Test Rules: Enforces assertions on observable outputs (rendered text, emitted events, store state) instead of internal implementation details like wrapper.vm. - Test Review Mode: Flags missing coverage, brittle selectors, and implementation-coupled assertions when reviewing existing tests. - Use Case: When adding a new Vue component that reads from a Pinia store, use this Skill to generate a mount-based test that seeds store state, triggers user interactions, and asserts emitted events without touching component internals. ## Quick Start Write a unit test for my Vue component that submits a form and updates a Pinia store, using createTestingPinia with spied actions.
