CodeCeption Unit Testing Visit page

I am using codeception for unit testing as well as functional, I have created a test via this command composer exec codecept g:test unit Dashboard which created the DashboardTest.

Now i have the following code in my test. Simply what i anm doing is to visit a page.

class DashboardTest extends \Codeception\Test\Unit
{
    protected $tester;

    public function testPhotoCanBeUploaded()
    {
        $this->visit('/');
    }
}

But the following error comes up :

[Error] Call to undefined method DashboardTest::visit()

#1 DashboardTest->testPhotoCanBeUploaded

What am i missing ?