If you plan to travel internationally, you will need to get tested no more than 3 days before you travel by air into the United States (US) and show your negative result to the airline before you board your flight, or be prepared to show documentation of recovery (proof of a recent positive viral test and a letter from your healthcare provider or a public health official stating that you were cleared to travel).  This includes US citizens and legal permanent residents.  For more information go to https://www.cdc.gov/coronavirus/2019-ncov/travelers/testing-international-air-travelers.html.  What guidelines are there in your country?