ESLint: bail out config setup if eslint-plugin-storybook is already imported

[Copilot]

When configureFlatConfig ran against a config that already imported eslint-plugin-storybook under a custom alias, it skipped adding a duplicate import but still appended ...storybook.configs["flat/recommended"] — referencing an undefined storybook variable.

Example of broken output:

// user's existing config
import sb from 'eslint-plugin-storybook';
export default [
  ...sb.configs['flat/recommended'],
  ...storybook.configs["flat/recommended"], // ← `storybook` is undefined!
];

Changes

• configureFlatConfig: Bails out immediately (returns code unchanged) by walking the full AST via traverse to detect if eslint-plugin-storybook is already referenced — covering both static import declarations and dynamic import() expressions (used by tools like eslint-flat-config-utils).
• configureEslintPlugin: Skips writing the flat config file when configureFlatConfig returns unchanged code — consistent with the existing early-return behavior in the .eslintrc.json and .eslintrc.js paths.
• Tests: Added test cases covering the "already statically imported" and "already dynamically imported" scenarios to verify no write occurs.

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Summary by CodeRabbit

• Bug Fixes

  • Improved ESLint plugin configuration to skip modification when the Storybook plugin is already imported.
  • Added validation to prevent unnecessary file writes when no configuration changes are required.

• Tests

  • Added test coverage for the already-imported plugin scenario in flat config.

[github-actions]

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☁️ Nx Cloud last updated this comment at 2026-03-10 13:33:34 UTC

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 282c049 and 944b91a.

📒 Files selected for processing (2)

• code/core/src/cli/eslintPlugin.test.ts
• code/core/src/cli/eslintPlugin.ts

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📝 Walkthrough

Walkthrough

The changes add early-return guards to the ESLint configuration setup functions to skip modification when eslint-plugin-storybook is already imported. Corresponding test coverage is added to verify this behavior prevents unnecessary file writes.

Changes

Cohort / File(s)	Summary
ESLint Plugin Implementation code/core/src/cli/eslintPlugin.ts	Adds bailout logic in configureFlatConfig to return unchanged code if eslint-plugin-storybook is already imported, and adds a guard in configureEslintPlugin to skip writing when no changes occur.
Test Coverage code/core/src/cli/eslintPlugin.test.ts	Adds test case asserting that writeFile is not called when eslint-plugin-storybook is already present in the flat-config ESLint setup.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• storybookjs/storybook#32878: Modifies the same configureEslintPlugin and configureFlatConfig functions and related flat-config test coverage.

✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
• 📝 Generate docstrings (commit on current branch)

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[huang-julien]

should we instead walk through the AST and look for ImportDeclaration?
Sometimes we can have import expressions.
Quite a lot of projects uses https://github.com/antfu/eslint-flat-config-utils that accepts import(...)

[valentinpalkovic]

Good catch! @copilot See above comment

[Copilot]

Good catch! Updated in fc1e789 to use traverse and walk the full AST. The check now covers both static ImportDeclaration nodes and dynamic import() expressions (represented in Babel's AST as a CallExpression with an Import callee). Added a test case for the dynamic import scenario using the eslint-flat-config-utils pattern.