Firms should conduct the impairment test for goodwill at least annually. Accounting standards require more frequent impairment testing if some events occur. Identify the main events upon which goodwill undergoes a test for its impairment.

NOTE: DON'T COPY-PASTE FROM THE INTERNET AND OTHER ANSWERS. I NEED A UNIQUE SOLUTION FOR EXAMPLE. I SAID NO COPY-PASTE FROM THE INTERNET. I NEED UNIQUE ANSWERS IN TEXT FORM.