fix: don't escape markdown underscores (#4896)

apps/web/package.json

@@ -12,6 +12,7 @@
     "prettier": "prettier --check \"**/*.{js,ts,tsx,md}\"  --cache",
     "prettier:fix": "prettier --write \"**/*.{js,ts,tsx,md}\"  --cache",
     "start": "next start --port 4783",
+    "test:dev": "vitest run",
     "typecheck": "tsc --pretty"
   },
   "dependencies": {
@@ -92,6 +93,7 @@
     "autoprefixer": "^10.4.19",
     "postcss": "^8.4.38",
     "tailwindcss": "^3.4.3",
-    "typescript": "^5.4.5"
+    "typescript": "^5.4.5",
+    "vitest": "^1.6.0"
   }
 }

apps/web/src/helpers/prosekit/markdown.spec.ts

@@ -0,0 +1,53 @@
+import { describe, expect, test } from 'vitest';
+
+import { htmlFromMarkdown, markdownFromHTML } from './markdown';
+
+describe('markdownFromHTML', () => {
+  test('should convert HTML to markdown', () => {
+    const html = '<p>Text <strong>Bold</strong> <em>italic</em></p>';
+    const markdown = markdownFromHTML(html);
+    expect(markdown).toMatchInlineSnapshot(`
+      "Text **Bold** *italic*
+      "
+    `);
+  });
+
+  test('should not escape mention handles with _', () => {
+    const html =
+      '<p>A normal handle: <span>@lens/foo</span></p>' +
+      '<p>A handle with underscore: <span>@lens/foo_bar</span></p>';
+    const markdown = markdownFromHTML(html);
+    expect(markdown).toContain('@lens/foo');
+    expect(markdown).toContain('@lens/foo_bar');
+    expect(markdown).toMatchInlineSnapshot(`
+      "A normal handle: @lens/foo
+
+      A handle with underscore: @lens/foo_bar
+      "
+    `);
+  });
+});
+
+describe('htmlFromMarkdown', () => {
+  test('should convert markdown to HTML', () => {
+    const markdown = 'Text **Bold** _italic_';
+    const html = htmlFromMarkdown(markdown);
+    expect(html).toMatchInlineSnapshot(`
+      "<p>Text <strong>Bold</strong> <em>italic</em></p>
+      "
+    `);
+  });
+
+  test('should not escape mention handles with _', () => {
+    const markdown = [
+      'A normal handle: @lens/foo',
+      'A handle with underscore: @lens/foo_bar'
+    ].join('\n\n');
+    const html = htmlFromMarkdown(markdown);
+    expect(html).toMatchInlineSnapshot(`
+      "<p>A normal handle: @lens/foo</p>
+      <p>A handle with underscore: @lens/foo_bar</p>
+      "
+    `);
+  });
+});

apps/web/src/helpers/prosekit/markdown.ts

@@ -6,14 +6,22 @@ import remarkParse from 'remark-parse';
 import remarkStringify from 'remark-stringify';
 import { unified } from 'unified';
 
+// By default, remark-stringify escapes underscores (i.e. "_" => "\_"). We want
+// to disable this behavior so that we can have underscores in mention handles.
+const unescapeUnderscore = (str: string) => {
+  return str.replace(/(^|[^\\])\\_/g, '$1_');
+};
+
 export const markdownFromHTML = (html: string): string => {
-  return unified()
+  const markdown = unified()
     .use(rehypeParse)
     .use(rehypeRemark)
     .use(remarkLinkProtocol)
     .use(remarkStringify)
     .processSync(html)
     .toString();
+
+  return unescapeUnderscore(markdown);
 };
 
 export const htmlFromMarkdown = (markdown: string): string => {

apps/web/vitest.config.ts

@@ -0,0 +1,9 @@
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig({
+  test: {
+    alias: { '@helpers': '/src/helpers' },
+    globals: true,
+    testTimeout: 30000
+  }
+});