fix tests

packages/tiptap/src/Utils/injectCSS.js

@@ -1,13 +1,15 @@
 export default function (css) {
-  const style = document.createElement('style')
-  style.type = 'text/css'
-  style.textContent = css
-  const { head } = document
-  const { firstChild } = head
+  if (process.env.NODE_ENV !== 'test') {
+    const style = document.createElement('style')
+    style.type = 'text/css'
+    style.textContent = css
+    const { head } = document
+    const { firstChild } = head
 
-  if (firstChild) {
-    head.insertBefore(style, firstChild)
-  } else {
-    head.appendChild(style)
+    if (firstChild) {
+      head.insertBefore(style, firstChild)
+    } else {
+      head.appendChild(style)
+    }
   }
 }

packages/tiptap/test/Editor.spec.js

@@ -1,3 +1,5 @@
+// MutationObserver is not supported by JSDom
+import MutationObserver from 'mutation-observer'
 import Editor from '../src/Editor'
 
 import {
@@ -19,6 +21,8 @@ import {
   History,
 } from '../../tiptap-extensions'
 
+global.MutationObserver = MutationObserver
+
 test('create editor', () => {
   const editor = new Editor()