refactor: Adopt Storybook internal for extracting description from JS…

…Doc comments

src/compiler/transform/define-meta/index.test.ts

@@ -53,23 +53,23 @@ describe(transformDefineMeta.name, () => {
     });
 
     expect(toJs(defineMetaVariableDeclaration as unknown as Program).value).toMatchInlineSnapshot(`
-			"const {Story, meta} = defineMeta({
-			  title: 'Example',
-			  component: Example,
-			  tags: ['autodocs'],
-			  args: {
-			    onclick: action("onclick"),
-			    onmouseenter: action("onmouseenter"),
-			    onmouseleave: action("onmouseleave")
-			  },
-			  parameters: {
-			    docs: {
-			      description: {
-			        component: "Description set explicitly in the comment above \`defineMeta\`"
-			      }
-			    }
-			  }
-			});"
-		`);
+      "const {Story, meta} = defineMeta({
+        title: 'Example',
+        component: Example,
+        tags: ['autodocs'],
+        args: {
+          onclick: action("onclick"),
+          onmouseenter: action("onmouseenter"),
+          onmouseleave: action("onmouseleave")
+        },
+        parameters: {
+          docs: {
+            description: {
+              component: "Description set explicitly in the comment above \`defineMeta\`.\\n\\nMultiline supported. And also Markdown syntax:\\n\\n* **Bold**,\\n* _Italic_,\\n* \`Code\`."
+            }
+          }
+        }
+      });"
+    `);
   });
 });

src/compiler/transform/define-meta/insert-description.ts

@@ -1,5 +1,5 @@
 import { logger } from '@storybook/client-logger';
-import dedent from 'dedent';
+import type { Comment } from 'estree';
 
 import {
   createASTObjectExpression,
@@ -102,7 +102,36 @@ export function insertDefineMetaJSDocCommentAsDescription(params: Params): void
   getDescriptionPropertyValue(defineMetaFirstArgumentObjectExpression).properties.push(
     createASTProperty('component', {
       type: 'Literal',
-      value: dedent(leadingComments[0].value),
+      value: extractDescription(leadingComments),
     })
   );
 }
+
+/**
+ * Adopted from: https://github.com/storybookjs/storybook/blob/next/code/lib/csf-tools/src/enrichCsf.ts/#L148-L164
+ * Adjusted for this addon, because here we use AST format from `estree`, not `babel`.
+ */
+function extractDescription(leadingComments: Comment[]) {
+  const comments = leadingComments
+    .map((comment) => {
+      if (
+        comment.type === 'Line' ||
+        // is not a JSDoc format - `/**` - by default parser omits the leading `/*` and ending `*/`
+        !comment.value.startsWith('*')
+      ) {
+        return null;
+      }
+
+      return (
+        comment.value
+          .split('\n')
+          // remove leading *'s and spaces from the beginning of each line
+          .map((line) => line.replace(/^(\s+)?(\*+)?(\s)?/, ''))
+          .join('\n')
+          .trim()
+      );
+    })
+    .filter(Boolean);
+
+  return comments.join('\n');
+}

src/compiler/transform/index.test.ts

@@ -74,7 +74,7 @@ describe(transformStoriesCode.name, () => {
         parameters: {
           docs: {
             description: {
-              component: "Description set explicitly in the comment above \`defineMeta\`"
+              component: "Description set explicitly in the comment above \`defineMeta\`.\\n\\nMultiline supported. And also Markdown syntax:\\n\\n* **Bold**,\\n* _Italic_,\\n* \`Code\`."
             }
           }
         }

stories/Example.stories.svelte

@@ -4,7 +4,15 @@
 
   import Example from './Example.svelte';
 
-  // Description set explicitly in the comment above `defineMeta`
+  /**
+   * Description set explicitly in the comment above `defineMeta`.
+   *
+   * Multiline supported. And also Markdown syntax:
+   *
+   * * **Bold**,
+   * * _Italic_,
+   * * `Code`.
+   */
   const { Story } = defineMeta({
     title: 'Example',
     component: Example,