Addon Vitest: Improve transformation logic to avoid duplicate tests

[yannbf]

Closes #28930

This work changes the transformation done in the plugin to:

• account for no tests in a file
• transform only the stories that should be included (uses tags at compile time)
• execute only tests if they are imported in the same

This fixes several bugs:

1 - test fails because there are no tests in the file

export default {
  tags: ['!test']
}

// ...

2 - test from another file execute when being imported from a story file

import { someConstant } from './Other.stories' // this causes unintended side effects
export default {}
export const MyStory = {}

Before:

After:

What I did

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/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 PR does not have a canary release associated. You can request a canary release of this pull request by mentioning the @storybookjs/core team here.

core team members can create a canary release here or locally with gh workflow run --repo storybookjs/storybook canary-release-pr.yml --field pr=<PR_NUMBER>

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initSize	169 MB	169 MB	3.37 kB	1.74	0%
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buildSbManagerSize	2.3 MB	2.3 MB	0 B	0.33	0%
buildSbPreviewSize	351 kB	351 kB	0 B	1.09	0%
buildStaticSize	0 B	0 B	0 B	-	-
buildPrebuildSize	4.46 MB	4.46 MB	138 B	1.23	0%
buildPreviewSize	3 MB	3 MB	0 B	1.02	0%
testBuildSize	0 B	0 B	0 B	-	-
testBuildSbAddonsSize	0 B	0 B	0 B	-	-
testBuildSbCommonSize	0 B	0 B	0 B	-	-
testBuildSbManagerSize	0 B	0 B	0 B	-	-
testBuildSbPreviewSize	0 B	0 B	0 B	-	-
testBuildStaticSize	0 B	0 B	0 B	-	-
testBuildPrebuildSize	0 B	0 B	0 B	-	-
testBuildPreviewSize	0 B	0 B	0 B	-	-

name	before	after	diff	z	%
createTime	6.7s	20.4s	13.6s	0.65	66.9%
generateTime	20s	18.2s	-1s -842ms	-1.81	🔰-10.1%
initTime	16.5s	15.9s	-598ms	-1.18	-3.8%
buildTime	13s	14.4s	1.4s	1.46	🔺9.9%
testBuildTime	0ms	0ms	0ms	-	-
devPreviewResponsive	7.8s	7.8s	-30ms	0.44	-0.4%
devManagerResponsive	5s	5.1s	119ms	0.65	2.3%
devManagerHeaderVisible	903ms	855ms	-48ms	0.39	-5.6%
devManagerIndexVisible	943ms	893ms	-50ms	0.36	-5.6%
devStoryVisibleUncached	1.2s	1.4s	214ms	0.63	14.4%
devStoryVisible	940ms	894ms	-46ms	0.37	-5.1%
devAutodocsVisible	695ms	891ms	196ms	1.29	🔺22%
devMDXVisible	697ms	719ms	22ms	-0.06	3.1%
buildManagerHeaderVisible	733ms	781ms	48ms	0.33	6.1%
buildManagerIndexVisible	739ms	791ms	52ms	0.39	6.6%
buildStoryVisible	807ms	879ms	72ms	0.58	8.2%
buildAutodocsVisible	718ms	810ms	92ms	1.13	11.4%
buildMDXVisible	633ms	726ms	93ms	1	12.8%

Greptile Summary

This PR enhances the Vitest addon for Storybook, focusing on improving the transformation logic and test execution efficiency. Key changes include:

• Implemented filtering of stories based on tags at compile time in code/core/src/csf-tools/vitest-plugin/transformer.ts
• Added extraction of preview-level tags in code/addons/vitest/src/plugin/index.ts
• Improved handling of cases with no valid tests in a file in code/core/src/csf-tools/vitest-plugin/transformer.ts
• Implemented a guard to prevent duplicate test executions in code/core/src/csf-tools/vitest-plugin/transformer.ts
• Updated testStory function in code/addons/vitest/src/plugin/test-utils.ts to use composeStory for more accurate story composition

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[greptile-apps]

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[greptile-apps]

style: Check if composedStory is undefined before accessing its properties