The Magento Functional Testing Framework (MFTF) allows great flexibility when writing XML tests for extensions. All parts of tests can be used, reused, and merged to best suit your needs and cut down on needless duplication.
Extension developers can utilitze these merge points to leverage existing tests and modify just the parts needed to test their extension. For instance, if your extension adds a form field to a Catalog admin page, you can modify the existing Catalog tests and add actions, data, etc as needed to test the custom field. This topic shows how to merge and reuse test elements when testing extensions.
Follow the links below for an example of how to merge:
Only Test, Action Group, and Data objects in the MFTF Framework can be extended. Extending can be very useful for extension developers since it will not affect existing tests.
Consult when to use Extends to use extends when deciding whether to merge or extend.