add test-single

Author: Francesca-Bit

package.json

@@ -52,7 +52,8 @@
     "build": "webpack --mode production",
     "prepare": "npm run clean && npm run test && npm run build",
     "coveralls-after": "nyc report --reporter=text-lcov | coveralls",
-    "npm:publish": "npm publish --access public"
+    "npm:publish": "npm publish --access public",
+    "test-single": "mocha $1"
   },
   "repository": {
     "type": "git",