Keep current selection when attrForSelected is reset (#163)

* add test

* return null when attrForSelected is null

* keep current selection when resetting attrForSelected

* update selected when attrForSelected becomes null

* TODO revert this once polymer-cli#927 is fixed

.travis.yml

@@ -1,7 +1,7 @@
 language: node_js
 sudo: required
 before_script:
-  - npm install -g polymer-cli
+  - npm install -g polymer-cli web-component-tester
   - polymer install --variants
 env:
   global:
@@ -18,8 +18,8 @@ addons:
     packages:
       - google-chrome-stable
 script:
-  - xvfb-run polymer test
+  - xvfb-run wct
   - >-
-    if [ "${TRAVIS_PULL_REQUEST}" = "false" ]; then polymer test -s 'default';
+    if [ "${TRAVIS_PULL_REQUEST}" = "false" ]; then wct -s 'default';
     fi
 dist: trusty

iron-selectable.html

@@ -186,7 +186,7 @@
      * @returns Returns the index of the item
      */
     indexOf: function(item) {
-      return this.items.indexOf(item);
+      return this.items ? this.items.indexOf(item) : -1;
     },
 
     /**
@@ -346,7 +346,10 @@
       if (!item) {
         return null;
       }
-
+      if (!this.attrForSelected) {
+        var i = this.indexOf(item);
+        return i === -1 ? null : i;
+      }
       var propValue = item[Polymer.CaseMap.dashToCamelCase(this.attrForSelected)];
       return propValue != undefined ? propValue : item.getAttribute(this.attrForSelected);
     },

test/attr-for-selected.html

@@ -108,6 +108,15 @@
           done();
         });
       });
+
+      test('setting attr-for-selected to null keeps current selection', function() {
+        selector.select('value0');
+        assert.equal(selector.selectedItem, items[0]);
+        assert.equal(selector.selected, 'value0');
+        selector.attrForSelected = null;
+        assert.equal(selector.selectedItem, items[0]);
+        assert.equal(selector.selected, 0);
+      });
     });
 
     suite('reflected properties as attributes', function() {