add tests

test/unit/events-elements.html

@@ -93,3 +93,19 @@
     });
   </script>
 </dom-module>
+
+<dom-module id="x-double">
+  <script>
+    Polymer({
+      is: 'x-double',
+      behaviors: [EventLoggerImpl],
+      setup: function() {
+        this.listen(this, 'foo', 'missing');
+        this.listen(this, 'foo', 'missing');
+      },
+      teardown: function() {
+        this.unlisten(this, 'foo', 'missing');
+      }
+    });
+  </script>
+</dom-module>

test/unit/events.html

@@ -141,6 +141,36 @@
           assert.deepEqual(el._removed[3], {target: 'div', event: 'bar'});
         });
       });
+
+      suite('Event Listener Cache', function() {
+        suiteSetup(function() {
+          el = document.createElement('x-double');
+          document.body.appendChild(el);
+          el.setup();
+        });
+
+        suiteTeardown(function() {
+          document.body.removeChild(el);
+        });
+
+        test('Event handler fires only once', function() {
+          el.fire('foo');
+          assert.equal(el._warned.length, 1, 'event should fire only once');
+        });
+
+        test('listen reuses handler cache', function() {
+          var expected = el._recallEventHandler(el, 'foo', el, 'missing');
+          el.listen(el, 'foo', 'missing');
+          var actual = el._recallEventHandler(el, 'foo', el, 'missing');
+          assert.equal(actual, expected, 'function was not cached');
+        });
+
+        test('unlisten keeps handler for caching', function() {
+          el.teardown();
+          var fn = el._recallEventHandler(el, 'foo', el, 'missing');
+          assert.ok(fn, 'should be cached');
+        });
+      });
     });
   </script>