Storybook 9 debuts revamped testing with Vitest, leaner core, and accessibility tools

Storybook 9 introduces a comprehensive overhaul of its testing features, beginning with deep Vitest integration. This partnership lets users run tests across all component stories at once, streamlining test workflows for frontend teams. Alongside this, accessibility checks can now be performed simultaneously across every story, with violations inspectable directly in the browser, helping developers comply with accessibility standards faster.

While the testing suite expands, visual testing has also been enhanced. Chromatic powers pixel-level scanning on all stories, enabling teams to catch even the smallest UI changes and prevent regressions. Storybook 9 now computes test coverage, providing line, function, and branch insights to help teams verify if component code is adequately exercised. For flexibility, a new test widget lets users trigger or configure tests for various story types directly from the user interface.

Following these testing advances, the core Storybook framework has become 48% leaner. Installs now require less disk space, and documentation or test features can be added as needed. Core improvements further boost usability with updated story generation, tags-based organization, and settings to define theme, viewport, or locale at the story level. Updates to Svelte, Next.js, and React Native support also wider integration needs.