This just another simple test for behat and mink combo with plain blackbox driver. To log in to a site and do check some behavior you can write this simple test, again no PHP needed for it. You will be logged in and checking what is on people admin page. Add it to your some.feature file and run behat.
Scenario: View users list Given I am on "/" When I go to "/user/login" And I fill in the following: | Username | admin | | Password | admin | And press "Log in" And follow "People" Then I should see "Last Access"