The Spaniard last drove a Formula 1 auto in April a year ago, a few months after his final race for McLaren at the end of the 2018 championship.
However, since signing with Renault earlier in the season, Alonso has also been involved in the strategy meetings and debriefs that the team has to ensure he is familiar with the team's working methods on his return next year.
Alonso's partnership with Renault is a homecoming of sorts for the 32-time Grand Prix victor who both his world championship titles with the manufacturer.
Fernando Alonso says he is already embedded within Renault on Formula 1 race weekends, albeit in virtual form, to get him up to speed with how the race operation works. It was hard pressure and hard work today, but I think the vehicle has potential as we see every weekend, but there's still some room to improve as we know and we will try to do it in the short-term.
Fernando Alonso was left beaming with excitement as he tested Renault's 2020 vehicle for the first time in Barcelona on Tuesday.
He scored two of his 32 F1 victories in the Spanish Grand Prix, in 2006 and 2013, and had five further podium finishes on the track.
"It's very special to be back in Barcelona". "I remember my first test with Benetton in 2000 in Barcelona".
Following his past and future employer Renault from a distance, Alonso is frequently in contact with the trackside team during race weekends.
Fernando Alonso is a two-time Formula 1 world champion. "I'm really looking forward".
He agreed in July to rejoin Renault next season when the team will compete as Alpine, the French manufacturer's sports auto brand. "I'm comfortable here with Renault". "Everything is a bit easier when you know the faces and the team".
He will return to F1 after spending time away from the sport to try conquer the rest of the motorsports world, having twice won the Le Mans 24 Hours and competing in the Indianapolis 500 and Dakar Rally inside the last 18 months.