Vitest Testing Patterns

Vitest tests for Remotion rendering should mock the bundler and renderer to validate render correctness without heavy side effects. Place test files in __tests__ directories or as *.test.ts files alongside components, using ESM and TypeScript.

Mocking AWS services in Vitest involves simulating external client behaviors, such as S3 interactions, to avoid real side effects. Focus tests on validating API response outcomes and server logic behavior rather than internal implementation details.

Vitest supports native ESM and TypeScript for testing Remotion and AWS integrations. This allows you to write maintainable unit and integration tests across components, server logic, and API endpoints without additional transpilation steps.

Structure unit tests by placing *.test.ts files alongside Remotion components and AWS server code. Emphasize small, fast-running tests that cover critical paths and validate behavior over implementation to improve reliability.

Tests break when focusing on internal implementation details rather than behavior. Validate outcomes like render correctness and API responses using mocked bundlers and renderers, ensuring tests remain robust and maintainable across changes.