Mocking: Fix sb.mock usage in Storybook's deployed in subpaths

[valentinpalkovic]

Closes #32631

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-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-32678-sha-bda76dca. Try it out in a new sandbox by running npx [email protected] sandbox or in an existing project with npx [email protected] upgrade.

More information

Published version	0.0.0-pr-32678-sha-bda76dca
Triggered by	@valentinpalkovic
Repository	storybookjs/storybook
Branch	valentin/fix-sb-mock-on-subpath-deployed-storybooks
Commit	bda76dca
Datetime	Thu Oct 9 08:03:09 UTC 2025 (1759996989)
Workflow run	18369640830

To request a new release of this pull request, mention the @storybookjs/core team.

core team members can create a new canary release here or locally with gh workflow run --repo storybookjs/storybook publish.yml --field pr=32678

Summary by CodeRabbit

• Bug Fixes
  • The injected mocker script now loads via a relative URL (./...), fixing failures when the app is hosted in subdirectories, behind reverse proxies, or on custom/static bases.
  • No public interfaces were changed.

[coderabbitai]

📝 Walkthrough

Walkthrough

Replaced the injected module entry path from an absolute-like path /vite-inject-mocker-entry.js to a relative path ./vite-inject-mocker-entry.js in the Vite inject-mocker plugin. No other logic, templates, or exports changed.

Changes

Cohort / File(s)	Summary of Changes
Vite inject mocker plugin code/core/src/core-server/presets/vitePlugins/vite-inject-mocker/plugin.ts	Switched injected module entry path from "/vite-inject-mocker-entry.js" → "./vite-inject-mocker-entry.js". No other modifications.

Sequence Diagram(s)

(Skipped — change is a single-file path adjustment that does not alter control flow.)

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch valentin/fix-sb-mock-on-subpath-deployed-storybooks

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📒 Files selected for processing (1)

• code/core/src/core-server/presets/vitePlugins/vite-inject-mocker/plugin.ts (1 hunks)

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📓 Path-based instructions (2)

**/*.{ts,tsx,js,jsx}

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Adhere to ESLint and Prettier rules across all JS/TS source files

Files:

• code/core/src/core-server/presets/vitePlugins/vite-inject-mocker/plugin.ts

**/*.{ts,tsx}

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Fix type errors and prefer precise typings instead of using any or suppressions, consistent with strict mode

Files:

• code/core/src/core-server/presets/vitePlugins/vite-inject-mocker/plugin.ts

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🔇 Additional comments (1)

code/core/src/core-server/presets/vitePlugins/vite-inject-mocker/plugin.ts (1)

14-14: LGTM! The fix correctly addresses the subpath deployment issue.

The change from an absolute path to a relative path ensures the script loads correctly when Storybook is deployed to a subpath. Relative paths resolve relative to the current document's location, whereas absolute paths would incorrectly resolve from the domain root.

Verify the fix in a deployed subpath environment.

Since the PR has no documented manual testing steps, please verify that:

1. The fix resolves the issue described in [Bug]: SB10 - Module mocking does not work when accessing deployed Storybook in subpath route #32631 (module mocking works in subpath deployments).
2. The fix doesn't break existing functionality (mocking still works in standard deployments and locally).
3. The canary release (0.0.0-pr-32678-sha-bda76dca) can be tested in the failing scenario from the issue.

You can test the canary by following the reproduction steps from issue #32631 using the published canary version.

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☁️ Nx Cloud last updated this comment at 2025-10-09 12:29:58 UTC