Testing Strategy #

Animation systems need two layers of tests.

Unit tests (fast, deterministic) #

Use Vitest for pure logic:

• layout math
• option resolution
• registry behavior (presence/shared-layout)

These exist in /packages/motion/src/**/*.test.js.

E2E tests (visual behavior) #

Use Playwright for browser behavior:

• phase transitions
• remove-after-exit semantics
• shared layout and FLIP flow
• reduced motion behavior

Unit tests alone cannot prove browser rendering/animation timing, so e2e coverage is required for production confidence.