ClousuresBlogJazzBandTest.java

public class JazzBandTest {

    @Test
    public void bandCreatesMusicianWithAccessToBandSetList() {
        List setList = Arrays.asList("Donna Lee",  "Dig");
        JazzBand theBop5 = new JazzBand(setList);
        JazzBand.Musician tom = theBop5.createMusician();
        assertTrue(setList == tom.getBandSetList());
    }
}

public class JazzBand {

    private List setList;

    public JazzBand(List setList) {
        this.setList = setList;
    }

    public Musician createMusician() {
        return new Musician();
    }

    public class Musician {

        private Musician() {}

        public List getBandSetList() {
            return setList;
        }
    }
}