diff --git a/test/unit/utils.html b/test/unit/utils.html
index 9ddb3c50..02b19c3d 100644
--- a/test/unit/utils.html
+++ b/test/unit/utils.html
@@ -66,9 +66,11 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
         called++;
       };
 
+      assert(window.el1.isDebouncerActive('foo') === false);
       window.el1.debounce('foo', cb);
       window.el1.debounce('foo', cb);
       window.el1.debounce('foo', cb);
+      assert(window.el1.isDebouncerActive('foo') === true);
 
       setTimeout(function() {
         assert.equal(called, 1, 'debounce should be called exactly once');