Allow nested structure for accordions (#25121)

This commit allows nested structures for accordions. Also a part of
the documentation about data-children is removed because this
functionality didn't work and it's not applicable anymore.

Tests with the collapse accordion are also a bit adjusted to the new
situation.

docs/4.0/components/collapse.md

@@ -113,33 +113,6 @@ Using the [card]({{ site.baseurl }}/docs/{{ site.docs_version }}/components/card
 </div>
 {% endexample %}
 
-You can also create accordions with custom markup. Add the `data-children` attribute and specify a set of sibling elements to toggle (e.g., `.item`). Then, use the same attributes and classes as shown above for connecting toggles to their associated content.
-
-{% example html %}
-<div id="exampleAccordion" data-children=".item">
-  <div class="item">
-    <a data-toggle="collapse" data-parent="#exampleAccordion" href="#exampleAccordion1" role="button" aria-expanded="true" aria-controls="exampleAccordion1">
-      Toggle item
-    </a>
-    <div id="exampleAccordion1" class="collapse show" role="tabpanel">
-      <p class="mb-3">
-        Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed pretium lorem non vestibulum scelerisque. Proin a vestibulum sem, eget tristique massa. Aliquam lacinia rhoncus nibh quis ornare.
-      </p>
-    </div>
-  </div>
-  <div class="item">
-    <a data-toggle="collapse" data-parent="#exampleAccordion" href="#exampleAccordion2" role="button" aria-expanded="false" aria-controls="exampleAccordion2">
-      Toggle item 2
-    </a>
-    <div id="exampleAccordion2" class="collapse" role="tabpanel">
-      <p class="mb-3">
-        Donec at ipsum dignissim, rutrum turpis scelerisque, tristique lectus. Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vivamus nec dui turpis. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus.
-      </p>
-    </div>
-  </div>
-</div>
-{% endexample %}
-
 ## Accessibility
 
 Be sure to add `aria-expanded` to the control element. This attribute explicitly conveys the current state of the collapsible element tied to the control to screen readers and similar assistive technologies. If the collapsible element is closed by default, the attribute on the control element should have a value of `aria-expanded="false"`. If you've set the collapsible element to be open by default using the `show` class, set `aria-expanded="true"` on the control instead. The plugin will automatically toggle this attribute on the control based on whether or not the collapsible element has been opened or closed (via JavaScript, or because the user triggered another control element also tied to the same collapsbile element). If the control element's HTML element is not a button (e.g., an `<a>` or `<div>`), the attribute `role="button"` should be added to the element.

js/src/collapse.js

@@ -130,7 +130,11 @@ const Collapse = (($) => {
       let activesData
 
       if (this._parent) {
-        actives = $.makeArray($(this._parent).children().children(Selector.ACTIVES))
+        actives = $.makeArray(
+          $(this._parent)
+            .find(Selector.ACTIVES)
+            .filter(`[data-parent="${this._config.parent}"]`)
+        )
         if (!actives.length) {
           actives = null
         }

js/tests/unit/collapse.js

@@ -516,12 +516,50 @@ $(function () {
     var done = assert.async()
     var accordionHTML = '<div id="accordion">'
         + '<div class="item">'
-        + '<a id="linkTrigger" data-parent="#accordion" data-toggle="collapse" href="#collapseOne" aria-expanded="false" aria-controls="collapseOne"></a>'
-        + '<div id="collapseOne" class="collapse" role="tabpanel" aria-labelledby="headingThree"></div>'
+        + '<a id="linkTrigger" data-toggle="collapse" href="#collapseOne" aria-expanded="false" aria-controls="collapseOne"></a>'
+        + '<div id="collapseOne" class="collapse" role="tabpanel" aria-labelledby="headingThree" data-parent="#accordion"></div>'
         + '</div>'
         + '<div class="item">'
-        + '<a id="linkTriggerTwo" data-toggle="collapse" data-parent="#accordion" href="#collapseTwo" aria-expanded="false" aria-controls="collapseTwo"></a>'
-        + '<div id="collapseTwo" class="collapse show" role="tabpanel" aria-labelledby="headingTwo"></div>'
+        + '<a id="linkTriggerTwo" data-toggle="collapse" href="#collapseTwo" aria-expanded="false" aria-controls="collapseTwo"></a>'
+        + '<div id="collapseTwo" class="collapse show" role="tabpanel" aria-labelledby="headingTwo" data-parent="#accordion"></div>'
+        + '</div>'
+        + '</div>'
+
+    $(accordionHTML).appendTo('#qunit-fixture')
+    var $trigger = $('#linkTrigger')
+    var $triggerTwo = $('#linkTriggerTwo')
+    var $collapseOne = $('#collapseOne')
+    var $collapseTwo = $('#collapseTwo')
+    $collapseOne.on('shown.bs.collapse', function () {
+      assert.ok($collapseOne.hasClass('show'), '#collapseOne is shown')
+      assert.ok(!$collapseTwo.hasClass('show'), '#collapseTwo is not shown')
+      $collapseTwo.on('shown.bs.collapse', function () {
+        assert.ok(!$collapseOne.hasClass('show'), '#collapseOne is not shown')
+        assert.ok($collapseTwo.hasClass('show'), '#collapseTwo is shown')
+        done()
+      })
+      $triggerTwo.trigger($.Event('click'))
+    })
+    $trigger.trigger($.Event('click'))
+  })
+
+  QUnit.test('should allow accordion to contain nested elements', function (assert) {
+    assert.expect(4)
+    var done = assert.async()
+    var accordionHTML = '<div id="accordion">'
+        + '<div class="row">'
+        + '<div class="col-lg-6">'
+        + '<div class="item">'
+        + '<a id="linkTrigger" data-toggle="collapse" href="#collapseOne" aria-expanded="false" aria-controls="collapseOne"></a>'
+        + '<div id="collapseOne" class="collapse" role="tabpanel" aria-labelledby="headingThree" data-parent="#accordion"></div>'
+        + '</div>'
+        + '</div>'
+        + '<div class="col-lg-6">'
+        + '<div class="item">'
+        + '<a id="linkTriggerTwo" data-toggle="collapse" href="#collapseTwo" aria-expanded="false" aria-controls="collapseTwo"></a>'
+        + '<div id="collapseTwo" class="collapse show" role="tabpanel" aria-labelledby="headingTwo" data-parent="#accordion"></div>'
+        + '</div>'
+        + '</div>'
         + '</div>'
         + '</div>'
 
@@ -548,20 +586,20 @@ $(function () {
     var done = assert.async()
     $('<div id="accordion">'
         + '<div class="item">'
-        + '<a id="linkTrigger" data-parent="#accordion" data-toggle="collapse" href="#collapseOne" aria-expanded="false" aria-controls="collapseOne"></a>'
-        + '<div id="collapseOne" class="collapse" role="tabpanel" aria-labelledby="headingThree">'
+        + '<a id="linkTrigger" data-toggle="collapse" href="#collapseOne" aria-expanded="false" aria-controls="collapseOne"></a>'
+        + '<div id="collapseOne" data-parent="#accordion" class="collapse" role="tabpanel" aria-labelledby="headingThree">'
         + '<div id="nestedAccordion">'
         + '<div class="item">'
-        + '<a id="nestedLinkTrigger" data-parent="#nestedAccordion" data-toggle="collapse" href="#nestedCollapseOne" aria-expanded="false" aria-controls="nestedCollapseOne"></a>'
-        + '<div id="nestedCollapseOne" class="collapse" role="tabpanel" aria-labelledby="headingThree">'
+        + '<a id="nestedLinkTrigger" data-toggle="collapse" href="#nestedCollapseOne" aria-expanded="false" aria-controls="nestedCollapseOne"></a>'
+        + '<div id="nestedCollapseOne" data-parent="#nestedAccordion" class="collapse" role="tabpanel" aria-labelledby="headingThree">'
         + '</div>'
         + '</div>'
         + '</div>'
         + '</div>'
         + '</div>'
         + '<div class="item">'
-        + '<a id="linkTriggerTwo" data-toggle="collapse" data-parent="#accordion" href="#collapseTwo" aria-expanded="false" aria-controls="collapseTwo"></a>'
-        + '<div id="collapseTwo" class="collapse show" role="tabpanel" aria-labelledby="headingTwo"></div>'
+        + '<a id="linkTriggerTwo" data-toggle="collapse" href="#collapseTwo" aria-expanded="false" aria-controls="collapseTwo"></a>'
+        + '<div id="collapseTwo" data-parent="#accordion" class="collapse show" role="tabpanel" aria-labelledby="headingTwo"></div>'
         + '</div>'
         + '</div>').appendTo('#qunit-fixture')
     var $trigger = $('#linkTrigger')