There are two ways of testing for the COVID-19 virus.
PCR polymerase chain reaction-tests
The first one tests if there is a presence of the virus in the sample and is important for understanding who is infected and might transmit the virus to others, the so called PCR polymerase chain reaction-tests.
The second way tests for antibodies to the virus to understand if you have had the virus and you might be immune, the so called serological of antibody tests. If you are immune you can potentially help others with treatment.