Writing the same test five times with different inputs is copying, not testing. Parameterized testing breaks that habit by letting you write a single assertion once and run it against as many datasets as the problem demands. JUnit 6 (the Jupiter framework) gives you a rich set of argument sources, clean display names, and enough flexibility to handle everything from a handful of strings to deeply nested domain objects.

For developers building Spring Boot services, getting good at parameterized testing pays compound interest. Service layer logic, validation rules, pricing calculations, and repository queries all share the same structure: given some input, expect some output.…