🤖 test: Add cover script.

Author: a-flying-potato

package.json

@@ -32,7 +32,8 @@
     "test": "ava",
     "esdoc": null,
     "lint": "true",
-    "prepare": "npm run build"
+    "prepare": "npm run build",
+    "cover": "NODE_ENV=cover c8 --all --src src --reporter lcov --reporter text-summary --reporter text npm test"
   },
   "license": "AGPL-3.0",
   "name": "@aureooms/js-operator",