Using parameters and adopting a modular approach to test case design is an effective way to boost reusability for large test-case libraries.
The most valuable test cases are broadly applicable and reusable across different cycles and releases. To effectively reuse test cases, test engineers must design them to be only as specific as required and generic enough to be reused in different situations with different data inputs. Instead of duplicating or copy/pasting test cases or steps, break them down into small, reusable pieces to give yourself the ability to assemble them into larger end-to-end testing scenarios.
Testers can break down test cases into logical, manageable functions or modules. These isolated modules can be used to create independent tests, and they can be reassembled to create larger master test cases.
Parameters provide additional flexibility to make your modules even more generic and reusable. They can contain editable default values that allow testers to meet the needs of various testing situations. When invoking a reuseable module that contains parameters, the master test case passes the parameters, which can affect how input or output data are displayed or processed during test execution.
You can nest as many child modules called under any master test case as desired and with multiple levels. Each set of steps unfolds during the test execution (with the parameter replaced) as displayed in the following diagram: