Setup test environment and provide first tests 🌟

package.json

@@ -27,7 +27,7 @@
     "dev": "run-p serve watch:*",
     "dev:ssr": "run-p serve:ssr watch:*",
     "lint": "eslint {src,packages} --fix",
-    "test": "run-p lint",
+    "test": "mocha",
     "css": "stylus src/themes/*.styl -u autoprefixer-stylus",
     "watch:css": "run-p 'css -- -o themes -w'",
     "watch:js": "node build/build.js",
@@ -51,6 +51,7 @@
   },
   "devDependencies": {
     "autoprefixer-stylus": "^0.14.0",
+    "chai": "^4.2.0",
     "chokidar": "^2.0.2",
     "conventional-changelog-cli": "^1.3.5",
     "cross-env": "^5.1.3",
@@ -61,6 +62,7 @@
     "jsdom": "^13.2.0",
     "lerna": "^2.5.1",
     "live-server": "^1.2.1",
+    "mocha": "^5.2.0",
     "npm-run-all": "^4.1.5",
     "rimraf": "^2.6.2",
     "rollup": "^0.53.3",
@@ -70,7 +72,8 @@
     "rollup-plugin-node-resolve": "^3.0.0",
     "rollup-plugin-replace": "^2.0.0",
     "rollup-plugin-uglify": "^2.0.1",
-    "stylus": "^0.54.5"
+    "stylus": "^0.54.5",
+    "xhr2": "^0.1.4"
   },
   "keywords": [
     "doc",