Why the test.jar is missing?

the path is queer


It is not JAR. It is dynamically generated classes that are created by enhancing Gradle task. If you build your project files will be generated.

Do you have any problems with this?

i creat a empty project ,then open in eclipse , it’s show this error,
Can i test junit ?

It is not an error. Sure, you can use junit for tests. See also: https://doc.cuba-platform.com/manual-6.8/integration_tests_mw.html