It was a third shut-out in the Newcastle number one's last four international outings, with Dúbravka pushing a 30-yard volley from Florian Grillitsch onto the right-hand post before substitute Marko Arnautovic hit the same post shortly afterwards.
Slovakia kick off their Euros campaign against Poland in St. Petersburg on Monday, 14th June and also face Sweden and Spain in Group A.
Sweden - whose opening game is against Spain - warmed up with a 3-1 win over Armenia in Stockholm on Saturday, with Emil Krafth coming on in the 72nd minute.
And Ryan Fraser was a 64th-minute substitute as Scotland beat ten-man Luxembourg 1-0 on Sunday, with the Newcastle man creating a couple of good opportunities late on.
The Tartan Army take on Czech Republic in their opening game at Hampden Park next Monday before a clash with England and a final group match against Croatia. They will be based at Rockliffe Hall, near Darlington, during the tournament.
Meanwhile at under-21 level, Oisín McEntee played the full game on Saturday as Republic of Ireland lost 1-0 to Denmark in Marbella.