Merge branch 'hotfix/322'

Close #322

Author: weierophinney

composer.json

@@ -30,7 +30,7 @@
   "require-dev": {
     "ext-dom": "*",
     "ext-libxml": "*",
-    "phpunit/phpunit": "^5.7.16 || ^6.0.8",
+    "phpunit/phpunit": "^5.7.16 || ^6.0.8 || ^7.2.7",
     "zendframework/zend-coding-standard": "~1.0"
   },
   "provide": {