Most of us download trustable antivirus but we don’t know that antivirus is in working condition or not.
There is one group called EICAR (European Expert Group For IT Security) made our work easy for testing antivirus working or not.
Just copy and paste below line into one blank text file. X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*
And save file as a .txt extension.
If your antivirus has real time protection then pop up coming that virus detected and it will say that this is EICAR test file.Otherwise manually check by right clicking on file.
More info on EICAR on this link.