feat: add tests for YAML front matter tokenizer and enhance parsing logic

src/renderer/src/components/RichEditor/extensions/__tests__/yaml-front-matter.test.ts

@@ -0,0 +1,84 @@
+import type { JSONContent } from '@tiptap/core'
+import { MarkdownManager } from '@tiptap/markdown'
+import { describe, expect, it } from 'vitest'
+
+import { YamlFrontMatter } from '../yaml-front-matter'
+
+const parseFrontMatters = (markdown: string) => {
+  const manager = new MarkdownManager({
+    extensions: [YamlFrontMatter]
+  })
+  const doc = manager.parse(markdown) as JSONContent
+  const frontMatterNodes = (doc.content || []).filter((node) => node.type === 'yamlFrontMatter')
+  return frontMatterNodes.map((node) => (node.attrs as { content?: string } | undefined)?.content?.trim())
+}
+
+describe('YamlFrontMatter markdown tokenizer', () => {
+  it('only parses the first front matter block at the very start of the document', () => {
+    const markdown = `---
+title: First
+---
+
+Body text
+
+---
+title: Second
+---
+More content`
+
+    const contents = parseFrontMatters(markdown)
+    expect(contents).toHaveLength(1)
+    expect(contents[0]).toBe('title: First')
+  })
+
+  it('ignores a front matter block when it is not at the beginning of the document', () => {
+    const markdown = `Intro paragraph
+
+---
+title: Should not parse
+---`
+
+    const contents = parseFrontMatters(markdown)
+    expect(contents).toHaveLength(0)
+  })
+
+  it('ignores consecutive front matter blocks after the first one', () => {
+    const markdown = `---
+first: yes
+---
+---
+second: no
+---`
+
+    const contents = parseFrontMatters(markdown)
+    expect(contents).toHaveLength(1)
+    expect(contents[0]).toBe('first: yes')
+  })
+
+  it('does not treat body content containing --- as additional front matter', () => {
+    const markdown = `---
+title: Only header
+---
+
+Paragraph text.
+
+---
+
+More text.`
+
+    const contents = parseFrontMatters(markdown)
+    expect(contents).toHaveLength(1)
+    expect(contents[0]).toBe('title: Only header')
+  })
+
+  it('treats later front matter markers as regular markdown when content already exists', () => {
+    const markdown = `Intro paragraph
+
+---
+title: Should not parse
+---`
+
+    const contents = parseFrontMatters(markdown)
+    expect(contents).toHaveLength(0)
+  })
+})

src/renderer/src/components/RichEditor/extensions/yaml-front-matter.ts

@@ -1,4 +1,4 @@
-import { mergeAttributes, Node } from '@tiptap/core'
+import { type MarkdownToken,mergeAttributes, Node } from '@tiptap/core'
 import { ReactNodeViewRenderer } from '@tiptap/react'
 
 import YamlFrontMatterNodeView from '../components/YamlFrontMatterNodeView'
@@ -27,7 +27,12 @@ export const YamlFrontMatter = Node.create({
       return result
     },
     // Parse YAML front matter
-    tokenize(src: string) {
+    tokenize(src: string, tokens: MarkdownToken[] = []) {
+      const hasExistingContent = tokens.some((token) => token.type && token.type !== 'space')
+      if (hasExistingContent) {
+        return undefined
+      }
+
       // Match: ---\n...yaml content...\n---
       const match = /^---\n([\s\S]*?)\n---(?:\n|$)/.exec(src)