As part of Harlequins 150th anniversary celebration, the Warriors will travel to Twickenham Stoop in London on Saturday 20 August.
Gregor Townsend's men will return to England a week later to play Gloucester Rugby at Kingsholm Stadium on Saturday 27 August, with Sila Puafisi set to face his old side.
Meanwhile, the draw for next season's European Rugby Champions Cup will take place on Wednesday 29 June in Neuchâtel.
The new GUINNESS PRO12 season kicks off on the weekend of 2/3/4 September