(add authorization tests for publishing concerts)

app/Http/Controllers/Backstage/PublishedConcertsController.php

@@ -6,18 +6,20 @@ use App\Concert;
 use Carbon\Carbon;
 use Illuminate\Http\Request;
 use App\Http\Controllers\Controller;
+use Illuminate\Support\Facades\Auth;
 
 class PublishedConcertsController extends Controller
 {
     public function store()
     {
-        $concert = Concert::find(request('concert_id'));
+        $concert = Auth::user()->concerts()->findOrFail(request('concert_id'));
 
         if ($concert->isPublished()) {
             abort(422);
         }
 
         $concert->publish();
+
         return redirect()->route('backstage.concerts.index');
     }
 }