JUnit
/ˈdʒeɪˌjuːnɪt/ · Noun · Development
Definitions
A unit testing framework for Java used to define test cases, assertions, fixtures, and automated test execution as part of the build. Modern JUnit versions also support parameterized tests, lifecycle hooks, and extension points for richer test infrastructure.
In plain English: It is the standard tool many Java developers use to write and run automated tests.
Example: "That regression is covered now; I added a JUnit test that reproduces the null-handling bug."