From 70edf1f8dc7a764dc065ba29b299d13da39f5366 Mon Sep 17 00:00:00 2001
From: Daniel Freedman <dfreedm@google.com>
Date: Wed, 21 Feb 2018 16:06:41 -0800
Subject: [PATCH] Add tests

Workaround IE11 not having `element.labels` and Safari not populating
`element.labels` in shadowroots
---
 lib/utils/gestures.html          | 55 ++++++++++++++++++++++++++++++--
 test/unit/gestures-elements.html | 15 +++++++++
 test/unit/gestures.html          | 23 +++++++++++++
 3 files changed, 90 insertions(+), 3 deletions(-)

diff --git a/lib/utils/gestures.html b/lib/utils/gestures.html
index b29a7a4d4e..94cd964dbd 100644
--- a/lib/utils/gestures.html
+++ b/lib/utils/gestures.html
@@ -97,10 +97,59 @@
   /** @type {(function(MouseEvent): void | undefined)} */
   GestureRecognizer.prototype.click;
 
-  // keep track of any labels hit by tghe mouseCanceller
+  // keep track of any labels hit by the mouseCanceller
   /** @type {!Array<!HTMLLabelElement>} */
   const clickedLabels = [];
 
+  /** @type {!Map<string, boolean>} */
+  const labellable = {
+    'button': true,
+    'input': true,
+    'keygen': true,
+    'meter': true,
+    'output': true,
+    'textarea': true,
+    'progress': true,
+    'select': true
+  };
+
+  /**
+   * @param {HTMLElement} el Element to check labelling status
+   * @return {boolean} element can have labels
+   */
+  function canBeLabelled(el) {
+    return labellable[el.localName] || false;
+  }
+
+  /**
+   * @param {HTMLElement} el Element that may be labelled.
+   * @return {!Array<!HTMLLabelElement>} Relevant label for `el`
+   */
+  function matchingLabels(el) {
+    /** @type {!Array<!HTMLLabelElement>} */
+    let labels = el.labels;
+    // IE doesn't have `labels` and Safari doesn't populate `labels` if element is in a shadowroot.
+    if (!labels || !labels.length) {
+      labels = [];
+      let root = el.getRootNode();
+      // find all labels that are ancestors
+      let cur = el.parentNode;
+      while (cur !== root) {
+        if (cur.localName === 'label') {
+          labels.push(/** @type {!HTMLLabelElement} */(cur));
+        }
+      }
+      // if there is an id on `el`, check for all labels with a matching `for` attribute
+      if (el.id) {
+        let matching = root.querySelectorAll(`label[for = ${el.id}]`);
+        for (let i = 0; i < matching.length; i++) {
+          labels.push(/** @type {!HTMLLabelElement} */(matching[i]));
+        }
+      }
+    }
+    return labels;
+  }
+
   // touch will make synthetic mouse events
   // `preventDefault` on touchend will cancel them,
   // but this breaks `<input>` focus and link clicks
@@ -127,8 +176,8 @@
           if (path[i].nodeType === Node.ELEMENT_NODE) {
             if (path[i].localName === 'label') {
               labels.push(path[i]);
-            } else if (path[i].labels) {
-              let ownerLabels = path[i].labels;
+            } else if (canBeLabelled(path[i])) {
+              let ownerLabels = matchingLabels(path[i]);
               for (let j = 0; j < ownerLabels.length; j++) {
                 clickFromLabel = clickFromLabel || clickedLabels.indexOf(ownerLabels[j]) > -1;
               }
diff --git a/test/unit/gestures-elements.html b/test/unit/gestures-elements.html
index 777f2de556..ccf03f36ea 100644
--- a/test/unit/gestures-elements.html
+++ b/test/unit/gestures-elements.html
@@ -212,3 +212,18 @@
   });
   </script>
 </dom-module>
+
+<dom-module id="x-native-label">
+  <template>
+    <label id="label" for="check"></label>
+    <input id="check" type="checkbox">
+  </template>
+  <script>
+    class XNativeLabel extends Polymer.Element {
+      static get is() {
+        return 'x-native-label';
+      }
+    }
+    customElements.define(XNativeLabel.is, XNativeLabel);
+  </script>
+</dom-module>
diff --git a/test/unit/gestures.html b/test/unit/gestures.html
index 4c8a92b4cb..b3ad058953 100644
--- a/test/unit/gestures.html
+++ b/test/unit/gestures.html
@@ -559,6 +559,29 @@
         assert.equal(count, 1);
         Polymer.Gestures.remove(window, 'tap', increment);
       });
+
+      test('native label click', function() {
+        let el = document.createElement('x-native-label');
+        document.body.appendChild(el);
+        let target = el.$.label;
+        let touches = [{
+          clientX: 0,
+          clientY: 0,
+          identifier: 1,
+          // target is set to the element with `addEventListener`, which is app
+          target
+        }];
+        let touchstart = new CustomEvent('touchstart', {bubbles: true, composed: true});
+        touchstart.changedTouches = touchstart.touches = touches;
+        target.dispatchEvent(touchstart);
+        let touchend = new CustomEvent('touchend', {bubbles: true, composed: true});
+        touchend.touches = touchend.changedTouches = touches;
+        target.dispatchEvent(touchend);
+        let click = new MouseEvent('click', {bubbles: true, composed: true});
+        target.dispatchEvent(click);
+        assert.equal(el.$.check.checked, true);
+        document.body.removeChild(el);
+      });
     });
   </script>