The team should produce a potentially shippable increment
The Development Team consists of professionals who do the work of delivering a potentially releasable Increment of “Done” product at the end of each Sprint...with all of the skills as a team necessary to create a product Increment.
The team should produce a "potentially shippable increment" at the end of the sprint. Without testing whatever the team produces is not shippable.
but i want to know exactly when acceptance tests are done into scrum
process...During the sprint cycle or at the end of the sprint cycle?
As @Bryan Oakley said you should do acceptance testing during the sprint.
is it possible to separate the team, i.e team for development and team
for testing? For example: from the first Sprint Planning we separates
them, team 1 for development and team 2 for testing, working at the
No, they should not be separate teams. The team needs all the skills needed to create a "potentially shippable increment" - design, dev, testing...etc - within the team.
Scrum does not allow separate testing teams. In fact, Scrum does not even allow testing sub-teams within the development team! Here is the quote from the Scrum Guide by Jeff Sutherland and Ken Schwaber, "Scrum recognizes no sub-teams in the Development Team, regardless of particular domains that need to be addressed like testing or business analysis; there are no exceptions to this rule".