Added new unit test system

Author: AlexanderYW

.babelrc

@@ -1 +1 @@
-{ "presets": ["@babel/preset-env"] }
+{ "presets": ["@vue/cli-plugin-babel/preset"] }

.eslintrc.js

@@ -30,7 +30,14 @@ module.exports = {
   },
   'overrides': [
     {
-      'files': ['*.vue'],
+      'files': [
+        '*.vue',
+        '**/__tests__/*.{j,t}s?(x)',
+        '**/tests/unit/**/*.spec.{j,t}s?(x)'
+      ],
+      env: {
+        mocha: true
+      },
       'rules': {
         'indent': 'off'
       }