add tests

src/index.ts

@@ -7,7 +7,9 @@ export default class Updater {
         }
         
         async getArchive(): Promise<void> {
-                const res = await fetch(`${this.archiveURL}.${this.feedType}`);
+                const res = await fetch(`${this.archiveURL}.${this.feedType}`, {
+                                       "mode": "cors"
+                });
                 console.log(res);
         }
 }