From 10a7ae44076b5d4a30dd8fa473b003fd7686d2f5 Mon Sep 17 00:00:00 2001
From: Hector Carmona <hcarmona@chromium.org>
Date: Wed, 9 Oct 2019 16:33:18 -0700
Subject: [PATCH 1/3] Populate aria-owns attribute on iron-list + test

---
 iron-list.js    |  7 +++++++
 test/basic.html | 34 +++++++++++++++++++++++++++++++++-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/iron-list.js b/iron-list.js
index 3ecff251..af67273b 100644
--- a/iron-list.js
+++ b/iron-list.js
@@ -1323,10 +1323,17 @@ Polymer({
         }
       });
     } else {
+      let order = [];
       this._iterateItems(function(pidx, vidx) {
         this.translate3d(0, y + 'px', 0, this._physicalItems[pidx]);
         y += this._physicalSizes[pidx];
+        if (this._physicalItems[pidx].id) {
+          order.push(this._physicalItems[pidx].id);
+        }
       });
+      if (order.length) {
+        this.setAttribute('aria-owns', order.join(' '));
+      }
     }
   },
 
diff --git a/test/basic.html b/test/basic.html
index 0b0cfdd5..b4804082 100644
--- a/test/basic.html
+++ b/test/basic.html
@@ -20,7 +20,7 @@
 
   <test-fixture id="trivialList">
     <template>
-      <x-list></x-list>
+      <x-list id$="tl[[index]]"></x-list>
     </template>
   </test-fixture>
 
@@ -145,6 +145,38 @@
       assert.equal(list.firstVisibleIndex, 99);
     });
 
+    test('expected aria-owns while scrolling', function() {
+      list.items = buildDataSet(100);
+      PolymerFlush();
+
+      const getExpectedAriaOwns = () => {
+        return
+            // Physical children.
+            Array.from(list.querySelectorAll('x-list'))
+
+            // Skip selected node.
+            .filter(child => child.getBoundingClientRect().top >= -10000)
+
+            // Sort by |top|.
+            .sort((left, right) => left.getBoundingClientRect().top - right.getBoundingClientRect().top)
+
+            // Get IDs.
+            .map(child => child.id)
+
+            // Create expected |aria-owned|.
+            .join(' ');
+      };
+
+      // Make sure we're virtualizing nodes.
+      assert.isTrue(Array.from(list.querySelectorAll('x-list')).length < list.items.length);
+
+      // Scroll by 7 because it's not a 'nice round number'.
+      for (let i = 0; i < list.items.length; i += 7) {
+        list.scrollToIndex(i);
+        assert.equal(list.getAttribute('aria-owns'), getExpectedAriaOwns());
+      }
+    });
+
     test('scroll to index while not attached', function() {
       var tmpList = document.createElement('iron-list');
       dom(tmpList).appendChild(document.createElement('template'));

From 5eb282e138fc69ccbf6ff21457914c0ad91b9d63 Mon Sep 17 00:00:00 2001
From: Hector Carmona <hcarmona@chromium.org>
Date: Thu, 10 Oct 2019 11:06:22 -0700
Subject: [PATCH 2/3] Format and Update test

---
 test/basic.html         | 14 +++++++++-----
 test/fixtures/x-list.js |  2 +-
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/test/basic.html b/test/basic.html
index b4804082..c78b2789 100644
--- a/test/basic.html
+++ b/test/basic.html
@@ -20,7 +20,7 @@
 
   <test-fixture id="trivialList">
     <template>
-      <x-list id$="tl[[index]]"></x-list>
+      <x-list></x-list>
     </template>
   </test-fixture>
 
@@ -150,15 +150,18 @@
       PolymerFlush();
 
       const getExpectedAriaOwns = () => {
-        return
+        return Array
             // Physical children.
-            Array.from(list.querySelectorAll('x-list'))
+            .from(list.querySelectorAll('div.item'))
 
             // Skip selected node.
             .filter(child => child.getBoundingClientRect().top >= -10000)
 
             // Sort by |top|.
-            .sort((left, right) => left.getBoundingClientRect().top - right.getBoundingClientRect().top)
+            .sort((left, right) => {
+              return left.getBoundingClientRect().top -
+                  right.getBoundingClientRect().top;
+            })
 
             // Get IDs.
             .map(child => child.id)
@@ -168,7 +171,8 @@
       };
 
       // Make sure we're virtualizing nodes.
-      assert.isTrue(Array.from(list.querySelectorAll('x-list')).length < list.items.length);
+      assert.isTrue(list.querySelectorAll('div.item').length < list.items.length);
+      assert.isTrue(list.querySelectorAll('div.item').length > 0);
 
       // Scroll by 7 because it's not a 'nice round number'.
       for (let i = 0; i < list.items.length; i += 7) {
diff --git a/test/fixtures/x-list.js b/test/fixtures/x-list.js
index e6d39c3c..9a77e978 100644
--- a/test/fixtures/x-list.js
+++ b/test/fixtures/x-list.js
@@ -41,7 +41,7 @@ Polymer({
 
     <iron-list items="[[data]]" as="item" id="list">
       <template>
-        <div class="item" selected\$="[[selected]]">
+        <div id$="xl[[index]]" class="item" selected\$="[[selected]]">
           <div style\$="[[_computedItemHeight(item)]]" tabindex\$="[[_computedTabIndex(tabIndex, useTabIndex)]]" hidden\$="[[primitive]]">[[item.index]]</div>
           <div style\$="[[_computedItemHeight(item)]]" tabindex\$="[[_computedTabIndex(tabIndex, useTabIndex)]]" hidden\$="[[!primitive]]">[[item]]</div>
         </div>

From 7d8a1ad00502dfa6b54018e267a81296f87c3a88 Mon Sep 17 00:00:00 2001
From: Hector Carmona <hcarmona@chromium.org>
Date: Fri, 11 Oct 2019 11:17:43 -0700
Subject: [PATCH 3/3] Address feedback

---
 iron-list.js | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/iron-list.js b/iron-list.js
index af67273b..f6336ff7 100644
--- a/iron-list.js
+++ b/iron-list.js
@@ -1323,12 +1323,14 @@ Polymer({
         }
       });
     } else {
-      let order = [];
+      const order = [];
       this._iterateItems(function(pidx, vidx) {
-        this.translate3d(0, y + 'px', 0, this._physicalItems[pidx]);
+        const item = this._physicalItems[pidx];
+        this.translate3d(0, y + 'px', 0, item);
         y += this._physicalSizes[pidx];
-        if (this._physicalItems[pidx].id) {
-          order.push(this._physicalItems[pidx].id);
+        const itemId = item.id;
+        if (itemId) {
+          order.push(itemId);
         }
       });
       if (order.length) {