chore: adding the report for issue 34258

README.md

@@ -1,3 +1,21 @@
+## CES Info
+
+### Group Members
+
+| Student               | ID        |
+| --------------------- | --------- |
+| Beatriz Oziel de Lima | 202510621 |
+| Rubens Brock Silva    | 202510624 |
+| Matvii Suk            | 202514197 |
+
+### Issues
+
+| Issue                                                           | Resources                           |
+| --------------------------------------------------------------- | ----------------------------------- |
+| [#34258](https://github.com/storybookjs/storybook/issues/34258) | [Report doc](issue-34258-report.md) |
+
+## Rest of the Original README
+
 <p align="center">
   <a href="https://storybook.js.org/?ref=readme">
     <picture>

issue-34258-report.md

@@ -0,0 +1,254 @@
+# Issue Report: Extract Shared Core Preset Factory
+
+## Issue
+
+> **Project:** [Storybook](https://github.com/storybookjs/storybook)
+> **Issue:** [#34258 — Duplicate Code: Framework core Preset Builder Options Pattern](https://github.com/storybookjs/storybook/issues/34258)  
+> **Status:** Implemented, tested locally, pull request submitted.
+
+The Storybook repo contains one `core` preset handler per framework package. Every such handler is responsible for:
+
+1. Resolving the active framework preset value from the preset system.
+2. Setting the builder (name + forwarded builder options).
+3. Optionally declaring a renderer.
+
+At the time this issue was filed, six framework packages contained an identical structural block:
+
+```ts
+export const core: PresetProperty<'core'> = async (config, options) => {
+  const framework = await options.presets.apply('framework');
+  return {
+    ...config,
+    builder: {
+      name: <BUILDER_NAME>,
+      options: typeof framework === 'string' ? {} : framework.options.builder || {},
+    },
+    renderer: <RENDERER_NAME>, // optional
+  };
+};
+```
+
+The duplicated inline ternary `typeof framework === 'string' ? {} : framework.options.builder || {}` was the primary concern raised in the issue. However, the broader structural duplication, the full `core` preset handler pattern, is a deeper maintainability problem where any future change to how the `core` preset is constructed (e.g., adding a new field, changing how the framework is resolved, or changing the builder options merge strategy) must be applied to six separate files.
+
+This is a **maintainability issue**, not a functional defect. All six implementations were equivalent at the time of discovery, but that equivalence is accidental and fragile.
+
+## Requirements
+
+- The resolved builder options must remain identical to the pre-refactor values for all supported framework configurations.
+- The duplicated builder-options resolution logic must be extracted into a shared helper function.
+- The full `core` preset handler pattern must be extractable into a factory function usable by all six framework packages.
+- The factory must support an optional async hook for frameworks that require additional side effects before returning (e.g. Next.js loading webpack config).
+- The helper must safely handle `null`/`undefined` framework values without throwing.
+- All six framework `core` preset handlers must use the shared factory.
+- Both helpers must be covered by automated unit tests.
+- All helpers must be placed in the existing shared utility layer (`storybook/internal/common`) following project conventions.
+
+## Source Code Files
+
+### Directly involved files
+
+- `code/frameworks/react-webpack5/src/preset.ts`: Webpack 5 preset for React. Declares `core` with duplicated structure.
+  - Replacing full `core` handler with `createCorePreset(...)` call.
+
+- `code/frameworks/server-webpack5/src/preset.ts`: Webpack 5 preset for Server renderer. Same pattern.
+  - Replacing full `core` handler with `createCorePreset(...)` call.
+
+- `code/frameworks/angular/src/preset.ts`: Webpack 5 preset for Angular. Same pattern, no renderer.
+  - Replacing full `core` handler with `createCorePreset(...)` call.
+
+- `code/frameworks/ember/src/preset.ts`: Webpack 5 preset for Ember. Same pattern, no renderer.
+  - Extending existing import, replacing `core` with `createCorePreset(...)`.
+
+- `code/frameworks/nextjs-vite/src/preset.ts`: Vite preset for Next.js. Same pattern.
+  - Replacing full `core` handler with `createCorePreset(...)` call.
+
+- `code/frameworks/nextjs/src/preset.ts`: Webpack 5 preset for Next.js. Same pattern + async `configureConfig` side effect.
+  - Using `createCorePreset(...)` with `beforeReturn` hook.
+
+- `code/core/src/common/utils/get-builder-options.ts`: Shared common utility. Exports `getBuilderOptions(options)`.
+  - Adding `getFrameworkBuilderOptions`, `CreateCorePresetOptions`, and `createCorePreset`.
+
+### Indirectly involved files (no changes required)
+
+- `code/core/src/common/index.ts`: Re-exports everything from `get-builder-options.ts` via `export * from './utils/get-builder-options'`. All new exports are automatically included.
+
+- `code/core/src/types/modules/core-common.ts`: Defines `Preset`, `CoreConfig`, `Options`, and `PresetPropertyFn`, the types used by the new helpers.
+
+### New files
+
+- `code/core/src/common/utils/get-builder-options.test.ts`: Unit tests for `getFrameworkBuilderOptions` (2 cases) and `createCorePreset` (4 cases).
+  - 6 tests total.
+
+## Design of the Fix
+
+### Strategy
+
+Two helpers are introduced, both in `code/core/src/common/utils/get-builder-options.ts`:
+
+1. **`getFrameworkBuilderOptions(framework: Preset)`** — a pure synchronous function that extracts builder options from a resolved framework preset value. This solves the inline ternary duplication.
+
+2. **`createCorePreset(options: CreateCorePresetOptions)`** — a factory function that encapsulates the entire `core` preset handler pattern. It calls `getFrameworkBuilderOptions` internally. Framework packages use this factory instead of writing the full async function, expressing only what is unique to them: the builder name, an optional renderer name, and an optional async hook.
+
+Placing both in `get-builder-options.ts` is appropriate because:
+
+- The file already handles the closely related concern of resolving builder options.
+- `createCorePreset` depends directly on `getFrameworkBuilderOptions`.
+- The existing barrel re-export in `index.ts` includes both automatically.
+- All six framework packages can already import from `storybook/internal/common`.
+
+### The `beforeReturn` hook
+
+Most framework presets map cleanly onto the `{ builderName, rendererName }` pattern. The Next.js webpack preset is an exception: it must call `configureConfig(...)` after resolving the framework but before returning. Rather than leaving Next.js outside the factory (which would create an inconsistency), the `beforeReturn` hook allows this side effect to be expressed as part of the factory call while keeping the factory itself generic.
+
+### Diagrams
+
+#### Dependency diagram
+
+```mermaid
+graph TD
+  A["react-webpack5 Preset"] --> F
+  B["server-webpack5 Preset"] --> F
+  C["angular Preset"] --> F
+  D["ember Preset"] --> F
+  E["nextjs-vite Preset"] --> F
+  N["nextjs Preset"] -->|beforeReturn hook| F
+  F["createCorePreset Helper"]
+  F --> G["getFrameworkBuilderOptions Helper"]
+  F -. exported via .-> H["storybook/internal/common"]
+  G -. exported via .-> H
+```
+
+#### Sequence Diagram
+
+```mermaid
+sequenceDiagram
+  participant Storybook
+  participant CorePreset as createCorePreset
+  participant Presets as options.presets.apply
+  participant Hook as beforeReturn?
+
+  Storybook->>CorePreset: invoke core preset (config, options)
+  CorePreset->>Presets: apply('framework')
+  Presets-->>CorePreset: resolved framework preset
+  CorePreset->>Hook: call beforeReturn(framework, options) [optional]
+  Hook-->>CorePreset: (sync/async) completion
+  CorePreset-->>Storybook: return core config with { builder: { name, options }, renderer? }
+```
+
+## Fix Source Code
+
+### `get-builder-options.ts`
+
+```ts
+import type {
+  CoreConfig,
+  Options,
+  Preset,
+  PresetPropertyFn,
+} from "storybook/internal/types";
+
+// --- existing getBuilderOptions function unchanged ---
+
+export function getFrameworkBuilderOptions(
+  framework: Preset,
+): Record<string, any> {
+  return typeof framework === "string"
+    ? {}
+    : (framework?.options?.builder ?? {});
+}
+
+export interface CreateCorePresetOptions {
+  builderName: string;
+  rendererName?: string;
+  beforeReturn?: (framework: Preset, options: Options) => Promise<void> | void;
+}
+
+export function createCorePreset({
+  builderName,
+  rendererName,
+  beforeReturn,
+}: CreateCorePresetOptions): PresetPropertyFn<"core"> {
+  return async (config, options) => {
+    const framework = await options.presets.apply("framework");
+
+    if (beforeReturn) {
+      await beforeReturn(framework, options);
+    }
+
+    return {
+      ...config,
+      builder: {
+        name: builderName,
+        options: getFrameworkBuilderOptions(framework),
+      },
+      ...(rendererName !== undefined ? { renderer: rendererName } : {}),
+    };
+  };
+}
+```
+
+### Framework preset files — before / after
+
+**Simpler cases:** react-webpack5, server-webpack5, angular, ember, nextjs-vite
+
+```diff
+-export const core: PresetProperty<'core'> = async (config, options) => {
+-  const framework = await options.presets.apply('framework');
+-  return {
+-    ...config,
+-    builder: {
+-      name: fileURLToPath(import.meta.resolve('@storybook/builder-webpack5')),
+-      options: typeof framework === 'string' ? {} : framework.options.builder || {},
+-    },
+-    renderer: fileURLToPath(import.meta.resolve('@storybook/react/preset')),
+-  };
+-};
++export const core = createCorePreset({
++  builderName: fileURLToPath(import.meta.resolve('@storybook/builder-webpack5')),
++  rendererName: fileURLToPath(import.meta.resolve('@storybook/react/preset')),
++});
+```
+
+**Special case:** nextjs - uses `beforeReturn` hook
+
+```diff
+-export const core: PresetProperty<'core'> = async (config, options) => {
+-  const framework = await options.presets.apply<StorybookConfig['framework']>('framework');
+-  // Load the Next.js configuration before we need it in webpackFinal...
+-  await configureConfig({
+-    baseConfig: {},
+-    nextConfigPath: typeof framework === 'string' ? undefined : framework.options.nextConfigPath,
+-  });
+-  return {
+-    ...config,
+-    builder: {
+-      name: fileURLToPath(import.meta.resolve('@storybook/builder-webpack5')),
+-      options: { ...(typeof framework === 'string' ? {} : framework.options.builder || {}) },
+-    },
+-    renderer: fileURLToPath(import.meta.resolve('@storybook/react/preset')),
+-  };
+-};
++export const core = createCorePreset({
++  builderName: fileURLToPath(import.meta.resolve('@storybook/builder-webpack5')),
++  rendererName: fileURLToPath(import.meta.resolve('@storybook/react/preset')),
++  // Load the Next.js configuration before we need it in webpackFinal...
++  beforeReturn: async (framework) => {
++    await configureConfig({
++      baseConfig: {},
++      nextConfigPath: typeof framework === 'string' ? undefined : framework.options?.nextConfigPath,
++    });
++  },
++});
+```
+
+### Validation results
+
+| Check                                  | Result                      |
+| -------------------------------------- | --------------------------- |
+| `get-builder-options.test.ts`          | **6/6 tests pass** (141 ms) |
+| Linter on all 8 modified/created files | **No errors**               |
+| Behaviour change                       | **None** - pure refactor    |
+
+## Submit the Fix
+
+This Pull Request [storybook!34310](https://github.com/storybookjs/storybook/pull/34310) was submitted to Storybook project's Github.