Build: Add E2E tests for Component Testing module

Closes https://github.com/storybookjs/storybook/issues/29213

What I did

This PR introduces changes in the sandbox script to register addon test in vite-based sandboxes, as well as add an E2E to test the entire flow. It also fixes a bug where the test runner was crashing.

Unfortunately I had to add a resolution to a beta version of Vitest 2.1. That's because Vitest 2.1 introduced a bug when changing from fast-glob to tinyglobby, which is a library that does not support symlinks. This means that the addon test stories are not picked up and therefore the E2E tests would fail.

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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createSize	0 B	0 B	0 B	-	-
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initSize	152 MB	153 MB	797 kB	16.89	0.5%
diffSize	74.6 MB	74.6 MB	2.56 kB	1.45	0%
buildSize	7.28 MB	7.28 MB	378 B	0.77	0%
buildSbAddonsSize	1.87 MB	1.87 MB	0 B	0.71	0%
buildSbCommonSize	195 kB	195 kB	0 B	-	0%
buildSbManagerSize	1.93 MB	1.93 MB	378 B	0.79	0%
buildSbPreviewSize	312 kB	312 kB	0 B	-	0%
buildStaticSize	0 B	0 B	0 B	-	-
buildPrebuildSize	4.31 MB	4.31 MB	378 B	0.79	0%
buildPreviewSize	2.98 MB	2.98 MB	0 B	0.68	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	21.2s	18.5s	-2s -685ms	0.35	-14.5%
generateTime	20.1s	20s	-80ms	0.99	-0.4%
initTime	15.4s	14.1s	-1s -311ms	-1.54	🔰-9.3%
buildTime	9.6s	9.2s	-363ms	-1.1	-3.9%
testBuildTime	0ms	0ms	0ms	-	-
devPreviewResponsive	7s	6.5s	-531ms	-0.42	-8.1%
devManagerResponsive	4.4s	4.2s	-242ms	-0.4	-5.7%
devManagerHeaderVisible	663ms	909ms	246ms	3.25	🔺27.1%
devManagerIndexVisible	718ms	935ms	217ms	2.93	🔺23.2%
devStoryVisibleUncached	1.3s	1.1s	-194ms	-1.02	-16.4%
devStoryVisible	716ms	943ms	227ms	3.06	🔺24.1%
devAutodocsVisible	694ms	740ms	46ms	1.59	🔺6.2%
devMDXVisible	584ms	526ms	-58ms	-0.59	-11%
buildManagerHeaderVisible	628ms	634ms	6ms	1.32	0.9%
buildManagerIndexVisible	632ms	672ms	40ms	1.14	6%
buildStoryVisible	678ms	673ms	-5ms	0.78	-0.7%
buildAutodocsVisible	515ms	579ms	64ms	0.47	11.1%
buildMDXVisible	560ms	476ms	-84ms	-1.71	🔰-17.6%

Greptile Summary

This PR introduces changes to register the addon test in vite-based sandboxes and adds E2E tests for the addon test functionality. Key modifications include:

Added basic test stories in code/addons/test/template/stories/basics.stories.ts
Enhanced VitestManager in code/addons/test/src/node/vitest-manager.ts for better Storybook integration
Updated sidebar Tree component in code/core/src/manager/components/sidebar/Tree.tsx for improved test status display
Introduced new E2E tests in code/e2e-tests/component-testing.spec.ts
Modified scripts/tasks/sandbox-parts.ts to include addon test in vite-based sandboxes

Note: PR is currently blocked due to a Vitest 2.1 bug affecting symlink support, preventing addon test stories from being picked up.

storybookjs / storybook