After winning her first Italian Open title against defending champion Karolina Pliskova, Halep discussed the COVID case at Roland Garros, saying: "I heard before the match and, of course, it worries me,"
"But I'm sure that measures will take place there, and we will be safe enough to be okay to play and to be safe.
"I don't know yet because I'm not there. After I get there, I will have a feeling."
A statement from French Open organisers did not name the player but explained she would quarantine for seven days, adding that five other players suffered the same fate the day before.
With world number one Ashleigh Barty electing not to defend her French title because of the virus, Halep will be the highest ranked player in the tournament and a favourite to win her second French Open title.
World number four Pliskova, who was playing in Rome with her left thigh heavily bandaged, also stressed the need for caution.
"You have to be really careful where you go, and still you don't know if you can get it or where you can get it and from who. I mean, that's the situation right now.
"But definitely not thinking not to go because of just, you know, having some people positive there... the plan is to go."
Men's qualifying began on Monday while the women start on Tuesday, trying to earn a place in the rescheduled clay-court major which runs from September 27 to October 11.
"In total, about 900 tests have been carried out since Thursday," tournament officials said.
Tournament director Guy Forget said earlier in September that players would be tested "upon their arrival and will receive their accreditation as soon as the first negative test is returned."
A second test will be carried out within 72 hours and then another every five days based on a player's progression in the tournament, he said.
Organisers hope to welcome back fans but have reduced the planned daily attendance from 20,000 to 5,000.