Add 'pretest' and 'test' scripts in package.json

Author: fredj

package.json

@@ -15,7 +15,9 @@
   "license": "BSD-2-Clause",
   "scripts": {
     "karma": "karma start test/karma.conf.js",
-    "lint": "eslint *.js"
+    "lint": "eslint *.js",
+    "pretest": "npm run lint",
+    "test": "npm run karma -- --single-run --log-level error"
   },
   "devDependencies": {
     "eslint": "^5.15.0",