One of the most fundamental changes in Agile development is in how testing is done. Because Agile teams move so fast, testing relies heavily, and often exclusively, on automation. If you are delivering working software every week, or if you’re pushing each change to production immediately in continuous deployment, manual testing isn’t a viable option.
Throwing code over to an independent test team at the end of a sprint is an anti-pattern in Agile. Testing has to be done in phase as changes are made. Hardening sprints, where the team blocks off time to focus on testing, debugging, and patching the code before it can be deployed to production, is another practice that most modern teams avoid.
Organizations that depend on independent test teams for quality assurance, and on manual penetration testing gates or scheduled scans or audits for security, need to change the way that they think and work.
In many Agile and DevOps teams, there are no testers. Developers take on the responsibility for testing their own code, because they have to. The Product Owner or someone else on the team playing the role of the “customer” may write acceptance test scenarios using tools supplied by the team. But developers are responsible for writing all the other tests and making sure that they pass. Testing becomes an integral part of coding, instead of a separate Waterfall phase.