Closes #

What I did

This PR adds a new autoblock that prevents users from upgrading to Storybook 9 if they have @storybook/experimental-addon-test installed and are using Vitest < 3. This is necessary because in Storybook 9, the experimental addon is being stabilized (renamed to @storybook/addon-vitest) and as part of this stabilization, we've dropped support for Vitest 2.

Changes

• Added new autoblock block-experimental-addon-test.ts that:
  • Checks for presence of @storybook/experimental-addon-test in dependencies
  • Verifies Vitest version using package manager
  • Blocks upgrade if Vitest < 3.0.0 is detected
• Added comprehensive test suite covering all scenarios
• Added clear user messaging explaining the required actions

Testing

The changes include a test suite that verifies:

• ✅ Returns false when experimental addon is not installed
• ✅ Returns false when Vitest is not installed
• ✅ Returns true (blocks) when Vitest < 3.0.0 is detected
• ✅ Returns false when Vitest >= 3.0.0 is detected
• ✅ Checks both dependencies and devDependencies
• ✅ Provides clear user guidance in the log message

User Impact

When users with @storybook/experimental-addon-test and Vitest < 3 attempt to upgrade to Storybook 9, they will see a message explaining:

• That the addon is being stabilized in Storybook 9
• The new name of the addon (@storybook/addon-vitest)
• Their options:
  1. Remove the experimental addon if not needed
  2. Upgrade to Vitest 3 to continue using the addon

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

• stories
• unit tests
• integration tests
• end-to-end tests

Manual testing

This section is mandatory for all contributions. If you believe no manual test is necessary, please state so explicitly. Thanks!

Documentation

• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Checklist for Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli-storybook/src/sandbox-templates.ts

• Make sure this PR contains one of the labels below:

  Available labels

  • bug: Internal changes that fixes incorrect behavior.
  • maintenance: User-facing maintenance tasks.
  • dependencies: Upgrading (sometimes downgrading) dependencies.
  • build: Internal-facing build tooling & test updates. Will not show up in release changelog.
  • cleanup: Minor cleanup style change. Will not show up in release changelog.
  • documentation: Documentation only changes. Will not show up in release changelog.
  • feature request: Introducing a new feature.
  • BREAKING CHANGE: Changes that break compatibility in some way with current major version.
  • other: Changes that don't fit in the above categories.

🦋 Canary release

This pull request has been released as version 0.0.0-pr-31068-sha-6e3bb0f4. Try it out in a new sandbox by running npx [email protected] sandbox or in an existing project with npx [email protected] upgrade.