The class FakeApp implements a CLI program using stdin and stdout for all it's interaction with the user.
This is unit-tested via the code:
@Test
public void lineByLineTests() {
try (TestCase testCase = TestCase.build()
.input("add-user oli glimmer").expect("user added")
.input("add-user heiner test").expect("user added")
.input("list-users").expect("user:", "1,oli,glimmer", "2,heiner,test")
.input("del-user 1").expect("user deleted")
.input("list-users").expect("user:", "2,heiner,test")
.input("quit")) {
FakeApp.main(null);
}
}(as seen in class UnitTest).
If you think this isn't unit testing and more component or even end-to-end testing - fair enough.