vm_perm = find_obj_in_resp response, 'Link', 'arvados#virtualMachine'
verify_link vm_perm, 'permission', 'can_login', resp_user[:uuid], vm.uuid
vm_perm = find_obj_in_resp response, 'Link', 'arvados#virtualMachine'
verify_link vm_perm, 'permission', 'can_login', resp_user[:uuid], vm.uuid