Cardi B is sick and tired over the mixed messages ... railing against the process over who can and can't get tested for the coronavirus. The rapper posted a 4-minute video explaining why she's confused and pissed when she hears about people who do NOT have any of the coronavirus symptoms but end up getting tested for the virus. Cardi B struggles to reconcile how President Trump is urging Americans who are not showing symptoms -- like coughing and fever -- to NOT get tested because there's a limited supply ... but then sees celebrities doing exactly that.