Laravel 5 | Test with POST

I Use PHPUnit testing with laravel5,

I get proper status code when i use "GET" method,

 $this->call('GET','admin'); 

 $this->assertResponseOk();        //Status Code: 200

If I try to get status code of the page by "POST" method,

       $param = [
        'id' => 2
        ];
    $this->call('POST', 'shopping/remove', array(), array(), array(),array(), $param);

    $this->assertResponseOk();      //Status Code: 500

Whats wrong with my code ....?

I wanna to do POST level submission test ...