public function testServingFile()
 {
     $response = new StaticFileResponse($this->testFilePath);
     $lastModified = new DateTime();
     $lastModified->setTimestamp(File::lastModified($this->testFilePath));
     $this->assertEquals($response->getStatusCode(), 200);
     $this->assertEquals($response->getContent(), $this->testFileContent);
     $this->assertEquals($response->getLastModified()->getTimestamp(), $lastModified->getTimestamp());
 }
<?php

use JsLocalization\StaticFileResponse;
Route::get('/js-localization/messages', 'JsLocalizationController@createJsMessages');
Route::get('/js-localization/localization.js', function () {
    $response = new StaticFileResponse(__DIR__ . "/../public/js/localization.min.js");
    $response->setPublic();
    $response->header('Content-Type', 'application/javascript');
    return $response;
});