The RT-PCR test is considered the gold standard for detection of SARS-CoV-2. But this was not based on an actual virus specimen or virus isolate ; the test was developed from the genome put up on the internet. The authors of the published paper concede this in their own paper.
Euro Surveill. 2020 Jan 23; 25(3): 2000045. doi: 10.2807/1560-7917.ES.2020.25.3.2000045
N Engl J Med 2020; 382:970-971 DOI: 10.1056/NEJMc2001468