How to test a method, that uses a Scanner?

[bartfastiel]

I want to test a method like this:

boolean bla() {
    Scanner s = new Scanner(System.in);
    return s.nextLine().contains("a");
}

The method has no arguments / parameters. How can I define the "given"-part of my test?

[bartfastiel]

Only test the logic, not the scanning of input.

If you refactor your code like this:

boolean blubb() {
    Scanner s = new Scanner(System.in);
    return blubb(s.nextLine());
}

boolean bla(String line) {
    return line.contains("a");
}

Then you can test method bla with a usual unit-test.