title: call_user_func() expects parameter 1 to be a valid callback - Laravel unit testing
body: <p>I am testing an API that returns a JOSN object, while running the following:     </p>
  
  <pre><code>public function testBasicExample()
      {
          $response = $this-&gt;call('GET', 'sites/1/webmaster/totalstats?since=2014-01-01&amp;until=2014-12-30');
      }
  </code></pre>
  
  <p>getting error:</p>
  
  <blockquote>
    <p>There was 1 error:</p>
    
    <p>1) ExampleTest::testBasicExample ErrorException: call_user_func()
    expects parameter 1 to be a valid callback, no array or string given</p>
    
    <p>/var/www/html/laravel/app/facade/Webmaster.php:527
    /var/www/html/laravel/app/helpers/WebmasterHelper.php:100
    /var/www/html/laravel/app/controllers/WebmasterController.php:129
    /var/www/html/laravel/app/routes.php:73
    /var/www/html/laravel/vendor/laravel/framework/src/Illuminate/Routing/Route.php:109
    /var/www/html/laravel/vendor/laravel/framework/src/Illuminate/Routing/Router.php:1033
    /var/www/html/laravel/vendor/laravel/framework/src/Illuminate/Routing/Router.php:1001
    /var/www/html/laravel/vendor/laravel/framework/src/Illuminate/Foundation/Application.php:775
    /var/www/html/laravel/vendor/laravel/framework/src/Illuminate/Foundation/Application.php:745
    /var/www/html/laravel/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/Client.php:81
    /var/www/html/laravel/vendor/symfony/browser-kit/Symfony/Component/BrowserKit/Client.php:327
    /var/www/html/laravel/vendor/laravel/framework/src/Illuminate/Foundation/Testing/ApplicationTrait.php:51
    /var/www/html/laravel/app/tests/ExampleTest.php:16</p>
    
    <p>FAILURES! Tests: 1, Assertions: 0, Errors: 1.</p>
  </blockquote>
  
  <p>I just started laravel a few days ago so I might do some very basic mistakes. Please help. Thanks</p>