Fix serializing empty fragment

Closes GH-26.

Reviewed-by: Titus Wormer <[email protected]>

Author: aguingand

packages/rehype-dom-stringify/lib/index.js

@@ -44,7 +44,7 @@ function serialize(node) {
   // Document.
   if ('doctype' in node) {
     const doctype = node.doctype ? serialize(node.doctype) : ''
-    const docelem = serialize(node.documentElement)
+    const docelem = node.documentElement ? serialize(node.documentElement) : ''
     return doctype + docelem
   }
 

test.js

@@ -125,6 +125,16 @@ test('rehype-dom-stringify', async function (t) {
     )
   })
 
+  await t.test('should support empty fragment', async function () {
+    assert.equal(
+      processor()
+        .data('settings', {fragment: true})
+        .processSync('')
+        .toString(),
+      ''
+    )
+  })
+
   await t.test('should stringify a fragment', async function () {
     assert.equal(
       processor()