This test should trigger 'window.onerror', and successfully handle the error. On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". window.onerror: "[object Event]" at undefined (Line: undefined, Column: undefined) No stack trace. Returning 'true': the error should not be reported in the console as an unhandled exception. PASS successfullyParsed is true TEST COMPLETE