Merge pull request #15987 from twbs/fix-15972

add role="button" to a[data-toggle="collapse"]

diff --cc js/tests/unit/collapse.js
index 5073bf10931c100264dbb58108bad17b84ca419a,be17fef1a394cf86e3cab8108d95b1e0a0111b68..0efa65400d3304d3a47418c7a1560e91a97c69e4
--- 1/js/tests/unit/collapse.js
--- 2/js/tests/unit/collapse.js
+++ b/js/tests/unit/collapse.js
@@@ -393,10 -366,10 +393,10 @@@ $(function () 
          showFired = true
        })
  
-     var $target2 = $('<a data-toggle="collapse" href="#body2" data-parent="#accordion"/>').appendTo($groups.eq(1))
+     var $target2 = $('<a role="button" data-toggle="collapse" href="#body2" data-parent="#accordion"/>').appendTo($groups.eq(1))
      var $body2   = $('<div id="body2" class="collapse"/>').appendTo($groups.eq(1))
  
 -    $target2.click()
 +    $target2.trigger('click')
  
      $body2
        .toggleClass('in collapsing')

diff --cc js/tests/visual/modal.html
Simple merge