fixes `npm test` on windows

package.json

@@ -13,7 +13,7 @@
     "start": "node loader.js",
     "lint": "eslint --cache .",
     "pretest": "npm run lint",
-    "test": "istanbul cover node_modules/mocha/bin/_mocha -- -R dot",
+    "test": "istanbul cover node_modules/mocha/bin/_mocha -- -R spec",
     "coveralls": "istanbul cover _mocha --report lcovonly -- -R dot && cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js && rm -rf ./coverage"
   },
   "dependencies": {