Fix failing battery tests. Add a dummy battery listener to avoid updates in the middle of a test case
diff --git a/autotest/tests/battery.tests.js b/autotest/tests/battery.tests.js
index 11c159b..47a86d4 100644
--- a/autotest/tests/battery.tests.js
+++ b/autotest/tests/battery.tests.js
@@ -21,15 +21,14 @@
 
 describe('Battery (navigator.battery)', function () {
 
-
+    // used to keep the count of event listeners > 0, in order to avoid battery level being updated with the real value when adding the first listener during test cases
+    var dummyOnEvent = jasmine.createSpy();
     beforeEach(function () {
-
+        window.addEventListener("batterycritical", dummyOnEvent, false);
     });
 
     afterEach(function () {
-        
-
-
+        window.removeEventListener("batterystatus", dummyOnEvent, false);
     });