Using Hamcrest matchers for stubbing and verification

In this recipe, we will use Hamcrest matchers in the stubbing and verification phases.

Getting ready

In this recipe, the system under test will be the NewPersonGenerator class that generates new identities for the given list of people. Also, we will send a web service message with the generated list of people, so their data gets updated, as shown in the following code:

public class NewPersonGenerator {

    private final NewIdentityCreator newIdentityCreator;

    public NewPersonGenerator(NewIdentityCreator newIdentityCreator) {
        this.newIdentityCreator = newIdentityCreator;
    }

    public List<Person> generateNewIdentities(List<Person> people) {
        List<Person> newPeople = new ArrayList<Person>();
      for(Person person : people) {
        String newName = newIdentityCreator.createNewName(person);
        int newAge = newIdentityCreator.createNewAge(person);
        List<Person> newSiblings...