Failed asserting that 'Home::index() is not found codeignitor unit testing

After spending few hours, I successfully installed everything from wget, phpunit, php version upgrade to 5.6, and http://ift.tt/1RL7kgb

when i ran phpunit for the first time (it ran welcome_test.php) it worked great and output as below

OK (2 tests, 2 assertions)

Then i created "Home_test.php" to test my controller and put below code

class Home_test extends TestCase
{
    public function tests_index(){
       $actual = "something";
       $expected = 'something';
       $this->assertEquals($expected, $actual);        
    }

    public function test_home(){
        $output = $this->request('GET', ['Home', 'index']);
        $this->assertContains('<title>Home</title>', $output);
    }
}

when i run phpunit i get below error

    PHPUnit 5.5.4 by Sebastian Bergmann and contributors.
    2 / 2 (100%)
    <?
    defined('BASEPATH') OR exit('No direct script access allowed');

    class Home extends CI_Controller {

        public function __construct(){
            parent::__construct();
        }

        public function index(){
           $data['user'] = $this->session->get_userdata();
           $this->load->view('header',$data);
           $this->load->view('home');
           $this->load->view('footer');
        }

    }

    Time: 354 ms, Memory: 24.00MB

    There was 1 failure:

    1) Home_test::test_home
    Failed asserting that 'Home::index() is not found' contains "<title>Home</title>".

    /Applications/AMPPS/www/tab/video2/application/tests/controllers/Home_test.php:13

    FAILURES!
    Tests: 2, Assertions: 2, Failures: 1.

If i point this test to

 $output = $this->request('GET', ['Welcome', 'index']); 

instead of

 $output = $this->request('GET', ['Home', 'index']);

then it works fine, that means Home_test.php and Welcome_test.php both are pointing to same controller, Welcome.php controller.

What i am doing wrong ?