test for v-for frozen object warning

test/unit/specs/directives/public/for/for_spec.js

@@ -990,6 +990,17 @@ describe('v-for', function () {
       done()
     })
   })
+
+  it('warning for frozen objects', function () {
+    new Vue({
+      el: document.createElement('div'),
+      template: '<div v-for="item in items">{{item.name}}</div>',
+      data: {
+        items: [Object.freeze({name:'hi'})]
+      }
+    })
+    expect('Frozen v-for objects cannot be automatically tracked').toHaveBeenWarned()
+  })
 })
 
 /**