Sufficient test coverage typically demands significant effort. Hundreds of test cases may be needed to exercise all use scenarios, validate boundary and edge cases, and ensure that an application is compatible across browsers and devices. Data-driven automated testing separates test procedures from test data, allowing you to cover more scenarios with a minimum amount of effort. Easily repeat test cases across browsers or devices to ensure your application’s compatibility and consistent performance.
Instead of creating the "tests" at the end, I suggest starting with examples at the beginning that can be run by a human or a software system. Get the programmer, tester, and product owner in a room to talk about what they need to be successful, to create examples, to define what the automation strategy will be, and to create a shared understanding to reduce failure demand. My preference is to do this at the story level — what some might call a minimum marketable feature — which requires a half-day to a week of work. George Dinwiddie, an agile coach in Maryland, popularized the term "the three amigos" for this style of work, referring to the programmer, tester, and analyst in these roles. Another term for the concept is acceptance test-driven development.
Selenium is possibly the most popular open-source test automation framework for Web applications. Being originated in the 2000s and evolved over a decade, Selenium has been an automation framework of choice for Web automation testers, especially for those who possess advanced programming and scripting skills. Selenium has become a core framework for other open-source test automation tools such as Katalon Studio, Watir, Protractor, and Robot Framework.