Data-Driven Testing & Parameterization in Selenium

What is Parameterization?

Parameterization means running the same test logic multiple times with different input values, rather than duplicating the test for each value.

Using TestNG's @DataProvider

@Test(dataProvider = "credentials")
public void login(String user, String pass) {
    loginPage.login(user, pass);
}

Using External Data Sources

Data can also be pulled from Excel, CSV, or JSON files using libraries like Apache POI, letting large sets of test data live outside the code entirely.

Why This Matters

Data-driven testing dramatically increases coverage (many input combinations) without multiplying the amount of test code that needs to be maintained.