Is there any squad team model which doesn't have tester or QA? Do they successful?
I'm researching a topic talking about the importance of a tester in a squad team, but I wonder if there's any squad doesn't have tester but still works well? And if so, how can they achieve that? Really appreciate any reply on this thread.
What is that "squad team" trying to achieve and what commitments, if any, are being made?
A Scrum Team will create Done increments of usable quality every Sprint. Scrum Team members recognize that quality assurance is the shared accountability of all Developers, regardless of whether or not any one of them is seen as being a "tester".
I'd be highly suspect of a team that doesn't have people who perform testing. However, I don't see a reason that a team needs a dedicated tester on the team. There's definitely value in having test specialists or subject matter experts in the organization, but there are many ways to have such specialists or experts support a team and not all of the ways require having that individual on the team.
I have worked with many teams that did not have individuals with QA in their title on the team. In fact, my previous 2 and current employer do not have any QA titles in our organization.
However, as noted by @Thomas Owens there are people that test. They are the same people that write code. They create automated tests, they have their peers review the code (including tests) and use that as a part of validating the quality of what is being done. They manually validate if there is a need to do so. Quality is owned by everyone in the Scrum Team and is part of the work that needs to be done in order to satisfy the Definition of Done.
Remember that Scrum does not have any job titles listed in the Guide anywhere. There are 3 roles, Product Owner, Scrum Master and Developers. The only plural roles, Developers, is meant to be made up by individuals that have the skills needed to create, maintain and release value increments. How your org decides to do this is up to you.
importance of a tester in a squad team
In scrum, there is no tester role. Yes you can take out that role. But what you think of quality of what you deliver ? Quality is everybody's responsibility in the team. So we believe testing is one of the ways to ensure quality.