And Parker admits competition for places has never been fiercer ahead of the tournament opener against Canada on August 20.
He said: "This will give ourselves and the Irish one last chance to try out different combinations in a real game.
"It's another opportunity to put our training into practice against a team that doesn't know our calls or what lines players will run.
"We're looking to see how all these things work in a match environment which will offer a real insight to our progress."
"The girls are as committed as any player I've ever worked with. They've worked immensely hard, their dedication and attitude to extra sessions has seen their fitness go up another notch since the 6 Nations.
"I spent some time speaking to supporters after the South Africa games who had never watched a women's international before and they were really impressed by the standard and commitment of good quality rugby players desperate to play for their country."
15 Nicola Halfpenny (Melrose)
14 Celia Hawthorn (Edinburgh University)
13 Lucy Millard (Team Northumbria)
12 Suzi Newton (Team Northumbria)
11 Lynsey Douglas (London Wasps)
10 Erin Kerr (London Wasps)
9 Sarah Gill (Murrayfield Wanderers)
1 Heather Lockhart (Hillhead / Jordanhill)
2 Sarah-Louise Walker (Watsonians)
3 Beth Dickens (Murrayfield Wanderers)
4 Louise Moffat (Murrayfield Wanderers)
5 Susannah Brown (Richmond)
6 Lynne Reid CAPTAIN (RHC Cougars)
7 Ruth Slaven (Murrayfield Wanderers)
8 Keri Holdsworth (Watsonians)
Donna Kennedy (Worcester), Rosalind Murphy (Edinburgh University), Gillian McCord (RHC Cougars), Alison Macdonald (RHC Cougars), Lindsay Wheeler (Darlington Mowden Sharks), Tess Forsberg (Murrayfield Wanderers), Stephanie Johnston (Hillhead / Jordanhill), Tanya Griffith (RHC Cougars), Louise Dalgliesh (RHC Cougars)