This feature is available in Ultimate edition only.
Regression Testing helps ensure that previously delivered features continue to work as new features are added. Teams can build and manage an inventory of regression tests, create test plans for each new release and manage the testing activities within the course of the team's sprint schedule.
Regression Tests are essentially templates for Acceptance Tests. They define the manual tests that can be organized and executed as part of regression planning activities. Regression Tests can be created from scratch or can be generated from Acceptance Tests that are defined on completed stories. Every time a Regression Test is added to a Test Suite or Test Set, it creates an Acceptance Test, with the parent story/backlog item or defect being the Test Set.
The regression test grid can be organized using tags and then grouped into specific regression suites that will be used as templates to generate the executable acceptance tests on test sets. In this way, regression tests act as long-term templates for verifying previously delivered functionality that can be run repeatedly in the form of acceptance tests.
You cannot associate Tests with Backlog Groups. You can, however, associate them to a Test Set, as a parent Backlog Item for Regression Tests.