StoryTest2.java

public class StoryTest2 {
    @Test
    public void shouldReturnHobbitCharacters() {
        List<Character> characters = Arrays.asList(BILBO, SAM, ARAGORN, GANDALF, FRODO);
        Story story = Story.builder().characters(characters).build();
        Set<Character> storyHobbits = story.charactersOf(Race.HOBBIT);
        assertThat(storyHobbits).containsOnly(BILBO, FRODO, SAM)
                                .extracting(Character::getRace)
                                .containsOnly(Race.HOBBIT);
    }
}