unit test idea for https://github.com/twitter/bootstrap/pull/7774

js_tests_unit_bootstrap-tooltip.js

test("reposition arrow test", function () {
  var tooltip = $('<a href="#" rel="tooltip" title="Simple tooltip" style="display: inline-block; position: absolute; top: 0; left: 100px;"></a>')
    .appendTo('#qunit-fixture')
    .tooltip({
      placement: 'bottom' 
    })
    .tooltip('show')
    
  equal($('.tooltip').children('.tooltip-arrow').length, 1, '.tooltip-arrow is present')
  equal($('.tooltip').children('.tooltip-arrow').position().left, '50%', '.tooltip-arrow positioned in the middle')

  tooltip.tooltip('hide')
  ok(!$(".tooltip").length, 'tooltip removed')
})