Bug 1359079 - Take <select multiple> into account for obscured click test; r=whimboo

Because individual <option> elements are painted and represented in the
DOM when they belong to a <select multiple> list, the center point of
the list might be one of the options.

To take this into account, we perform an inclusive descendant check
(DOMElement.contains) to see if the <option> element is a descendant of
the container <select> element.

In the case the targetted element is the element itself, the test will
still pass since it is an _inclusive_ descendant check.  In other words,
containerEl.contains(tree[0]), if tree[0] is equal to containerEl,
will pass.

The relevant specification changes were made in
40abcefd6a.

MozReview-Commit-ID: ORX8zLxQJ

--HG--
extra : rebase_source : 87ca38df6696257d569ef1ffcb888426d1f569af

testing/marionette/element.js

@@ -949,15 +949,19 @@ element.isVisible = function (el, x = undefined, y = undefined) {
  * point of its rectangle that is inside the viewport, excluding the size
  * of any rendered scrollbars.
  *
+ * An element is obscured if the pointer-interactable paint tree at its
+ * centre point is empty, or the first element in this tree is not an
+ * inclusive descendant of itself.
+ *
  * @param {DOMElement} el
  *     Element determine if is pointer-interactable.
  *
  * @return {boolean}
- *     True if interactable, false otherwise.
+ *     True if element is obscured, false otherwise.
  */
-element.isPointerInteractable = function (el) {
+element.isObscured = function (el) {
   let tree = element.getPointerInteractablePaintTree(el);
-  return tree[0] === el;
+  return !el.contains(tree[0]);
 };
 
 /**

testing/marionette/harness/marionette_harness/tests/unit/test_click.py

@@ -269,6 +269,24 @@ class TestClick(TestLegacyClick):
             button.click()
         self.assertFalse(self.marionette.execute_script("return window.clicked", sandbox=None))
 
+    def test_inclusive_descendant(self):
+        self.marionette.navigate(inline("""
+            <select multiple>
+              <option>first
+              <option>second
+              <option>third
+             </select>"""))
+        select = self.marionette.find_element(By.TAG_NAME, "select")
+
+        # This tests that the pointer-interactability test does not
+        # cause an ElementClickInterceptedException.
+        #
+        # At a <select multiple>'s in-view centre point, you might
+        # find a fully rendered <option>.  Marionette should test that
+        # the paint tree at this point _contains_ <option>, not that the
+        # first element of the paint tree is _equal_ to <select>.
+        select.click()
+
 
 class TestClickNavigation(MarionetteTestCase):
 

testing/marionette/interaction.js

@@ -157,7 +157,7 @@ function* webdriverClickElement (el, a11y) {
   let rects = containerEl.getClientRects();
   let clickPoint = element.getInViewCentrePoint(rects[0], win);
 
-  if (!element.isPointerInteractable(containerEl)) {
+  if (element.isObscured(containerEl)) {
     throw new ElementClickInterceptedError(containerEl, clickPoint);
   }