Study indicates asymptomatic carriers of SARS-CoV-2 are not infectious
pubmed.ncbi.nlm.nih.gov
pubmed.ncbi.nlm.nih.gov
But keep in mind if a virus is spreading in a community exponentially and the latency from exposure/infection to symptoms is greater in length than the doubling time then half of everyone who would test positive is going to be pre-symptomatic (and infectious).