Lucas di Grassi will do the driving when F1 tyre supplier Pirelli resumes its private track testing programme.
We reported in January that the former Virgin driver could be set to replace Pedro de la Rosa, who later announced he has returned to McLaren as third driver.
Spaniard de la Rosa was however given permission to drive Pirelli's 2009 Toyota test car in Turkey last week, but also at the Istanbul track for a few laps was Brazilian di Grassi.
And the 26-year-old Sao Paulo native "will take over test driving duties at the next test in Barcelona, scheduled for May", Pirelli confirmed at Sepang.
He is a nice guy, very intelligent and good enough for F1
"He is a nice guy, very intelligent and good enough for F1," Pirelli motor sport director Paul Hembery is quoted as saying by the Brazilian Totalrace website.
"We'll see what the rapport is," added the Briton, "how consistent he is and what feedback he gives. I'm hoping it's the right solution.
"We don't want to keep changing the driver all the time, but if Luca is as successful as the others, he will probably return to GP2 or formula one," predicted Hembery.
Pirelli's other F1 test drivers so far were Nick Heidfeld and Romain Grosjean.