How do I write a unit test to verify that a function sorts its result?

I have a data source from which I can request a list of people that live in a (any) country, and a method which retrieves the people from that data source and sorts them by their name alphabetically. How should I write my unit test to make sure that the sorting part of my method works properly?

This is what my SUT looks like:

class PeopleStuff {

    public IData data;

    public List<Person> getSortedPeopleForCountry(String countryName) {
        List<Person> people = data.getPeopleForCountry(countryName);

        Comparator nameComparator = new PersonNameComparator();
        Collections.sort(people, nameComparator);

        return people;
    }

}

And this is what my unit test looks like:

@Test public void testGetPeopleSortsByPeopleName() {
    String COUNTRY = "Whatistan";

    // set up test (the 3 lines below are actually in a @Before setup method)
    PeopleStuff peopleStuff = new PeopleStuff();
    IData mockData = createNiceMock(IData.class);
    peopleStuff.data = mockData;

    // set up data
    List<PersonName> mockPeopleList = new ArrayList<PersonName>();
    mockPeopleList.add(new Person(COUNTRY, "A"));
    mockPeopleList.add(new Person(COUNTRY, "D"));
    mockPeopleList.add(new Person(COUNTRY, "B"));
    mockPeopleList.add(new Person(COUNTRY, "C"));

    when(mockData.getPeopleForCountry(COUNTRY)).thenReturn(mockPeopleList);

    // exercise
    List<String> result = peopleStuff.getSortedPeopleForCountry(COUNTRY);

    // assert
    assertEquals("A", result.get(0).name);
    assertEquals("B", result.get(1).name);
    assertEquals("C", result.get(2).name);
    assertEquals("D", result.get(3).name);
}

What I need to know is if the way I am stubbing the data, running the test and making the assertions is correct, or if there are better ways of doing this.

My application has a lot of methods to test and a lot of custom sorting algorithm