fix(componentRegistry): gracefully recover if no md-component-id is specified

Author: ThomasBurleson

src/components/sidenav/sidenav.js

@@ -333,6 +333,8 @@ function ComponentRegistry($log, $q) {
      * @param handle the handle to identify the instance under.
      */
     register: function(instance, handle) {
+      if ( !handle ) return angular.noop;
+
       instance.$$mdHandle = handle;
       instances.push(instance);
 

src/components/sidenav/sidenav.spec.js

@@ -260,19 +260,50 @@ describe('mdSidenav', function() {
     }));
 
     it('should wait for next component registration', inject(function($mdComponentRegistry, $timeout) {
+      var resolved = undefined, count = 0;
       var promise = $mdComponentRegistry.when('left');
       var el = setup('md-component-id="left"');
-      var instance = $mdComponentRegistry.get('left');
-      var resolved = undefined;
+
+      promise.then(function(inst){ count += 1; });
+      $timeout.flush();
 
       el.triggerHandler('$destroy');
 
+      el = setup('md-component-id="left"');
       promise = $mdComponentRegistry.when('left');
-      promise.then(function(inst){   resolved = inst;  });
+      promise.then(function(inst){
+        resolved = inst;
+        count += 1;
+      });
 
       $timeout.flush();
 
+      expect(resolved).toBeDefined();
+      expect(count).toBe(2);
+
+    }));
+
+    it('should not find a component without an id', inject(function($mdComponentRegistry, $timeout) {
+      var el = setup();
+
+      var resolved = undefined, count = 0;
+      var promise = $mdComponentRegistry.when('left');
+      var instance = $mdComponentRegistry.get('left');
+
+      promise.then(function(inst){ resolved = inst; count += 1; });
+      $timeout.flush();
+
+      expect(count).toBe(0);
+      expect(instance).toBe(null);
       expect(resolved).toBeUndefined();
+
+    }));
+
+    it('should properly destroy without a md-component-id', inject(function($mdComponentRegistry, $timeout) {
+      var el = setup();
+
+      el.triggerHandler('$destroy');
+
     }));
 
   });