fix: treat heading children as inline elements

Author: farnabaz

src/runtime/stringify/mdc-remark.ts

@@ -153,7 +153,7 @@ const mdcRemarkNodeHandlers = {
     }
 
     const isInlineElement = (parent?.children || [])
-      .some(child => child.type === 'text') || ['p', 'li', 'strong', 'em', 'span'].includes(parent?.tagName)
+      .some(child => child.type === 'text') || ['p', 'li', 'strong', 'em', 'span', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6'].includes(parent?.tagName)
     if (isInlineElement) {
       return {
         type: mdastTextComponentType,

test/markdown/markdown.test.ts

@@ -0,0 +1,22 @@
+import { expect, it } from 'vitest'
+import { parseMarkdown } from '../utils/parser'
+import { stringifyMarkdown } from '../../src/runtime/stringify'
+
+
+it('Element in heading', async () => {
+  const { body } = await parseMarkdown('### :hello')
+  expect(body).toHaveProperty('type', 'root')
+
+  expect(body.children).toHaveLength(1)
+  expect(body.children[0]).toMatchObject({
+    type: 'element',
+    tag: 'h3',
+    props: { id: '' },
+    children: [{ type: 'element', tag: 'hello', props: {}, children: [] }],
+  })
+
+  const result = await stringifyMarkdown(body)
+  expect(result).toMatchInlineSnapshot(`
+    "### :hello\n"
+  `)
+})