SvelteKit: Fix set_context_after_init error when experimental async is enabled

code/frameworks/sveltekit/build-config.ts

@@ -45,6 +45,9 @@ const config: BuildEntries = {
       },
     ],
   },
+  extraOutputs: {
+    './internal/MockProvider.svelte': './static/MockProvider.svelte',
+  },
 };
 
 export default config;

code/frameworks/sveltekit/package.json

@@ -32,6 +32,7 @@
       "types": "./dist/index.d.ts",
       "default": "./dist/index.js"
     },
+    "./internal/MockProvider.svelte": "./static/MockProvider.svelte",
     "./internal/mocks/app/forms": "./dist/mocks/app/forms.js",
     "./internal/mocks/app/navigation": "./dist/mocks/app/navigation.js",
     "./internal/mocks/app/stores": "./dist/mocks/app/stores.js",
@@ -46,11 +47,11 @@
   },
   "files": [
     "dist/**/*",
+    "static/**/*",
     "template/**/*",
     "README.md",
     "*.js",
-    "*.d.ts",
-    "src/mocks/**/*"
+    "*.d.ts"
   ],
   "scripts": {
     "check": "jiti ../../../scripts/check/check-package.ts",

code/frameworks/sveltekit/src/preview.ts

@@ -1,138 +1,17 @@
 import type { Decorator } from '@storybook/svelte';
+import MockProvider from '@storybook/sveltekit/internal/MockProvider.svelte';
 
-import { action } from 'storybook/actions';
-import { onMount } from 'svelte';
-
-import { setAfterNavigateArgument } from './mocks/app/navigation';
-import { setNavigating, setPage, setUpdated } from './mocks/app/stores';
-import type { HrefConfig, NormalizedHrefConfig, SvelteKitParameters } from './types';
-
-const normalizeHrefConfig = (hrefConfig: HrefConfig): NormalizedHrefConfig => {
-  if (typeof hrefConfig === 'function') {
-    return { callback: hrefConfig, asRegex: false };
-  }
-  return hrefConfig;
-};
+import type { SvelteKitParameters } from './types';
 
 const svelteKitMocksDecorator: Decorator = (Story, ctx) => {
   const svelteKitParameters: SvelteKitParameters = ctx.parameters?.sveltekit_experimental ?? {};
-  setPage(svelteKitParameters?.stores?.page);
-  setNavigating(svelteKitParameters?.stores?.navigating);
-  setUpdated(svelteKitParameters?.stores?.updated);
-  setAfterNavigateArgument(svelteKitParameters?.navigation?.afterNavigate);
-
-  onMount(() => {
-    const globalClickListener = (e: MouseEvent) => {
-      // we add a global click event listener and we check if there's a link in the composedPath
-      const path = e.composedPath();
-      const element = path.findLast((el) => el instanceof HTMLElement && el.tagName === 'A');
-      if (element && element instanceof HTMLAnchorElement) {
-        // if the element is an a-tag we get the href of the element
-        // and compare it to the hrefs-parameter set by the user
-        const to = element.getAttribute('href');
-        if (!to) {
-          return;
-        }
-        e.preventDefault();
-        const defaultActionCallback = () => action('navigate')(to, e);
-        if (!svelteKitParameters.hrefs) {
-          defaultActionCallback();
-          return;
-        }
-
-        let callDefaultCallback = true;
-        // we loop over every href set by the user and check if the href matches
-        // if it does we call the callback provided by the user and disable the default callback
-        Object.entries(svelteKitParameters.hrefs).forEach(([href, hrefConfig]) => {
-          const { callback, asRegex } = normalizeHrefConfig(hrefConfig);
-          const isMatch = asRegex ? new RegExp(href).test(to) : to === href;
-          if (isMatch) {
-            callDefaultCallback = false;
-            callback?.(to, e);
-          }
-        });
-        if (callDefaultCallback) {
-          defaultActionCallback();
-        }
-      }
-    };
-
-    /**
-     * Function that create and add listeners for the event that are emitted by the mocked
-     * functions. The event name is based on the function name
-     *
-     * Eg. storybook:goto, storybook:invalidateAll
-     *
-     * @param baseModule The base module where the function lives (navigation|forms)
-     * @param functions The list of functions in that module that emit events
-     * @param {boolean} [defaultToAction] The list of functions in that module that emit events
-     * @returns A function to remove all the listener added
-     */
-    function createListeners(
-      baseModule: keyof SvelteKitParameters,
-      functions: string[],
-      defaultToAction?: boolean
-    ) {
-      // the array of every added listener, we can use this in the return function
-      // to clean them
-      const toRemove: Array<{
-        eventType: string;
-        listener: (event: { detail: any[] }) => void;
-      }> = [];
-      functions.forEach((func) => {
-        // we loop over every function and check if the user actually passed
-        // a function in sveltekit_experimental[baseModule][func] eg. sveltekit_experimental.navigation.goto
-        const hasFunction =
-          (svelteKitParameters as any)[baseModule]?.[func] &&
-          (svelteKitParameters as any)[baseModule][func] instanceof Function;
-        // if we default to an action we still add the listener (this will be the case for goto, invalidate, invalidateAll)
-        if (hasFunction || defaultToAction) {
-          // we create the listener that will just get the detail array from the custom element
-          // and call the user provided function spreading this args in...this will basically call
-          // the function that the user provide with the same arguments the function is invoked to
-
-          // eg. if it calls goto("/my-route") inside the component the function sveltekit_experimental.navigation.goto
-          // it provided to storybook will be called with "/my-route"
-          const listener = ({ detail = [] as any[] }) => {
-            const args = Array.isArray(detail) ? detail : [];
-            // if it has a function in the parameters we call that function
-            // otherwise we invoke the action
-            const fnToCall = hasFunction
-              ? (svelteKitParameters as any)[baseModule][func]
-              : action(func);
-            fnToCall(...args);
-          };
-          const eventType = `storybook:${func}`;
-          toRemove.push({ eventType, listener });
-          // add the listener to window
-          (window.addEventListener as any)(eventType, listener);
-        }
-      });
-      return () => {
-        // loop over every listener added and remove them
-        toRemove.forEach(({ eventType, listener }) => {
-          // @ts-expect-error apparently you can't remove a custom listener to the window with TS
-          window.removeEventListener(eventType, listener);
-        });
-      };
-    }
-
-    const removeNavigationListeners = createListeners(
-      'navigation',
-      ['goto', 'invalidate', 'invalidateAll', 'pushState', 'replaceState'],
-      true
-    );
-    const removeFormsListeners = createListeners('forms', ['enhance']);
-    window.addEventListener('click', globalClickListener);
-
-    return () => {
-      window.removeEventListener('click', globalClickListener);
-      removeNavigationListeners();
-      removeFormsListeners();
-    };
-  });
 
-  return Story();
+  return {
+    Component: MockProvider,
+    props: {
+      svelteKitParameters,
+    },
+  };
 };
 
 export const decorators: Decorator[] = [svelteKitMocksDecorator];

code/frameworks/sveltekit/static/MockProvider.svelte

@@ -0,0 +1,129 @@
+<script>
+  import { onMount } from 'svelte';
+  import { action } from 'storybook/actions';
+
+  import { setAfterNavigateArgument } from '@storybook/sveltekit/internal/mocks/app/navigation';
+  import { setNavigating, setPage, setUpdated } from '@storybook/sveltekit/internal/mocks/app/stores';
+
+
+  const{ svelteKitParameters = {}, children } = $props();
+
+
+  // Set context during component initialization - this happens before any child components
+  setPage(svelteKitParameters?.stores?.page);
+  setNavigating(svelteKitParameters?.stores?.navigating);
+  setUpdated(svelteKitParameters?.stores?.updated);
+  setAfterNavigateArgument(svelteKitParameters?.navigation?.afterNavigate);
+
+  const normalizeHrefConfig = (hrefConfig) => {
+    if (typeof hrefConfig === 'function') {
+      return { callback: hrefConfig, asRegex: false };
+    }
+    return hrefConfig;
+  };
+
+  onMount(() => {
+    const globalClickListener = (e) => {
+      // we add a global click event listener and we check if there's a link in the composedPath
+      const path = e.composedPath();
+      const element = path.findLast((el) => el instanceof HTMLElement && el.tagName === 'A');
+      if (element && element instanceof HTMLAnchorElement) {
+        // if the element is an a-tag we get the href of the element
+        // and compare it to the hrefs-parameter set by the user
+        const to = element.getAttribute('href');
+        if (!to) {
+          return;
+        }
+        e.preventDefault();
+        const defaultActionCallback = () => action('navigate')(to, e);
+        if (!svelteKitParameters.hrefs) {
+          defaultActionCallback();
+          return;
+        }
+
+        let callDefaultCallback = true;
+        // we loop over every href set by the user and check if the href matches
+        // if it does we call the callback provided by the user and disable the default callback
+        Object.entries(svelteKitParameters.hrefs).forEach(([href, hrefConfig]) => {
+          const { callback, asRegex } = normalizeHrefConfig(hrefConfig);
+          const isMatch = asRegex ? new RegExp(href).test(to) : to === href;
+          if (isMatch) {
+            callDefaultCallback = false;
+            callback?.(to, e);
+          }
+        });
+        if (callDefaultCallback) {
+          defaultActionCallback();
+        }
+      }
+    };
+
+    /**
+     * Function that create and add listeners for the event that are emitted by the mocked
+     * functions. The event name is based on the function name
+     *
+     * Eg. storybook:goto, storybook:invalidateAll
+     *
+     * @param baseModule The base module where the function lives (navigation|forms)
+     * @param functions The list of functions in that module that emit events
+     * @param {boolean} [defaultToAction] The list of functions in that module that emit events
+     * @returns A function to remove all the listener added
+     */
+    function createListeners(baseModule, functions, defaultToAction) {
+      // the array of every added listener, we can use this in the return function
+      // to clean them
+      const toRemove = [];
+      functions.forEach((func) => {
+        // we loop over every function and check if the user actually passed
+        // a function in sveltekit_experimental[baseModule][func] eg. sveltekit_experimental.navigation.goto
+        const hasFunction =
+          svelteKitParameters[baseModule]?.[func] &&
+          svelteKitParameters[baseModule][func] instanceof Function;
+        // if we default to an action we still add the listener (this will be the case for goto, invalidate, invalidateAll)
+        if (hasFunction || defaultToAction) {
+          // we create the listener that will just get the detail array from the custom element
+          // and call the user provided function spreading this args in...this will basically call
+          // the function that the user provide with the same arguments the function is invoked to
+
+          // eg. if it calls goto("/my-route") inside the component the function sveltekit_experimental.navigation.goto
+          // it provided to storybook will be called with "/my-route"
+          const listener = ({ detail = [] }) => {
+            const args = Array.isArray(detail) ? detail : [];
+            // if it has a function in the parameters we call that function
+            // otherwise we invoke the action
+            const fnToCall = hasFunction
+              ? svelteKitParameters[baseModule][func]
+              : action(func);
+            fnToCall(...args);
+          };
+          const eventType = `storybook:${func}`;
+          toRemove.push({ eventType, listener });
+          // add the listener to window
+          window.addEventListener(eventType, listener);
+        }
+      });
+      return () => {
+        // loop over every listener added and remove them
+        toRemove.forEach(({ eventType, listener }) => {
+          window.removeEventListener(eventType, listener);
+        });
+      };
+    }
+
+    const removeNavigationListeners = createListeners(
+      'navigation',
+      ['goto', 'invalidate', 'invalidateAll', 'pushState', 'replaceState'],
+      true
+    );
+    const removeFormsListeners = createListeners('forms', ['enhance']);
+    window.addEventListener('click', globalClickListener);
+
+    return () => {
+      window.removeEventListener('click', globalClickListener);
+      removeNavigationListeners();
+      removeFormsListeners();
+    };
+  });
+</script>
+
+{@render children()}

code/frameworks/sveltekit/tsconfig.json

@@ -4,7 +4,6 @@
     "paths": {
       "storybook/internal/*": ["../../lib/cli/core/*"]
     },
-    "rootDir": "./src"
   },
   "extends": "../../tsconfig.json",
   "include": ["src/**/*"]

scripts/tasks/sandbox-parts.ts

@@ -17,7 +17,11 @@ import { SupportedLanguage } from '../../code/core/src/cli/project_types';
 import { JsPackageManagerFactory } from '../../code/core/src/common/js-package-manager';
 import storybookPackages from '../../code/core/src/common/versions';
 import type { ConfigFile } from '../../code/core/src/csf-tools';
-import { formatConfig, writeConfig } from '../../code/core/src/csf-tools';
+import {
+  readConfig as csfReadConfig,
+  formatConfig,
+  writeConfig,
+} from '../../code/core/src/csf-tools';
 import type { TemplateKey } from '../../code/lib/cli-storybook/src/sandbox-templates';
 import type { PassedOptionValues, Task, TemplateDetails } from '../task';
 import { executeCLIStep, steps } from '../utils/cli-step';
@@ -170,19 +174,24 @@ export const init: Task['run'] = async (
   const cwd = sandboxDir;
 
   let extra = {};
-  if (template.expected.renderer === '@storybook/html') {
-    extra = { type: 'html' };
-  } else if (template.expected.renderer === '@storybook/server') {
-    extra = { type: 'server' };
-  } else if (template.expected.framework === '@storybook/react-native-web-vite') {
-    extra = { type: 'react_native_web' };
+
+  switch (template.expected.renderer) {
+    case '@storybook/html':
+      extra = { type: 'html' };
+      break;
+    case '@storybook/server':
+      extra = { type: 'server' };
+      break;
+    case '@storybook/svelte':
+      await prepareSvelteSandbox(cwd);
+      break;
   }
 
   switch (template.expected.framework) {
     case '@storybook/react-native-web-vite':
+      extra = { type: 'react_native_web' };
       await prepareReactNativeWebSandbox(cwd);
       break;
-    default:
   }
 
   await executeCLIStep(steps.init, {
@@ -878,6 +887,36 @@ async function prepareReactNativeWebSandbox(cwd: string) {
   }
 }
 
+async function prepareSvelteSandbox(cwd: string) {
+  const svelteConfigJsPath = join(cwd, 'svelte.config.js');
+  const svelteConfigTsPath = join(cwd, 'svelte.config.ts');
+
+  // Check which config file exists
+  const configPath = (await pathExists(svelteConfigTsPath))
+    ? svelteConfigTsPath
+    : (await pathExists(svelteConfigJsPath))
+      ? svelteConfigJsPath
+      : null;
+
+  if (!configPath) {
+    throw new Error(
+      `No svelte.config.js or svelte.config.ts found in sandbox: ${cwd}, cannot modify config.`
+    );
+  }
+
+  const svelteConfig = await csfReadConfig(configPath);
+
+  // Enable async components
+  // see https://svelte.dev/docs/svelte/await-expressions
+  svelteConfig.setFieldValue(['compilerOptions', 'experimental', 'async'], true);
+
+  // Enable remote functions
+  // see https://svelte.dev/docs/kit/remote-functions
+  svelteConfig.setFieldValue(['kit', 'experimental', 'remoteFunctions'], true);
+
+  await writeConfig(svelteConfig);
+}
+
 async function prepareAngularSandbox(cwd: string, templateName: string) {
   const angularJson = await readJson(join(cwd, 'angular.json'));