Johnson has named a 31-strong squad that will face hosts South Africa, Samoa and Italy but has opted to leave some of the familiar faces from this year's RBS 6 Nations at home.
Hookers Steven Lawrie and Pat MacArthur are both in line to make their Scotland debuts along with lock Tim Swindon, full-back Greig Tonks, wing Duncan Taylor and Glasgow Warriors quartet Alex Dunbar, Peter Horne, Peter Murchie and Tommy Seymour.
And with all eyes on building towards the 2015 World Cup, where Scotland are in the same pool as South Africa and Samoa, Johnson is keen to see how his new charges perform.
"First up, it's a strong squad designed to win Test matches against quality opposition," he said.
"We've continued to monitor the players' form closely and we've been pleased that Glasgow have reached the knockout stages of the Rabo.
"We are taking the opportunity to have a look at some players and want to assess what they're like at this level. We need to be able to find out whether players who've done the business for their clubs can replicate that form in international footy.
"We also want to enable certain players who are known to us - for example Nick De Luca and Max Evans - to have the sort of off-season physical preparation that they've not had for a few years because of the demands of touring schedules."