我正在学习java测试驱动开发，我被赋予了创建测试代码以通过的任务，但到目前为止，他们都失败了。不幸的是，我搞不清楚我把事情搞砸了。你们能告诉我从哪里开始吗？以下是我迄今为止的测试代码：

public class VirtualPetShelterTest {

    private VirtualPetShelter underTest;

    @BeforeEach
    public void setUp() {
        VirtualPetShelter underTest = new VirtualPetShelter();
        VirtualPet myPet = new VirtualPet("Bulma", 50, 50, 50);
        VirtualPet myPet2 = new VirtualPet("Arasu", 50, 50, 50);
        Collection<Object> pets = underTest.pets();
    }

    //intake//
    @Test
    public void shouldBeAbleToIntakePetToTheShelter() {
        VirtualPet myPet = new VirtualPet("Bulma", 50, 50, 50);
        VirtualPet myPet2 = new VirtualPet("Arasu", 50, 50, 50);
        int beginningSize = underTest.getAllPets().size();
        underTest.addPetToShelter(myPet);
        underTest.addPetToShelter(myPet2);
        int endingSize = underTest.getAllPets().size();
        assertTrue(endingSize > beginningSize);
    }

///

public class VirtualPetShelter {

    Map<String, VirtualPet> shelter = new HashMap<String, VirtualPet>();
    private Map<Object, Object> pets;

    public Collection<Object> pets() {
        return pets.values();
    }

    public HashMap <String, VirtualPet> getAllPets() {
        return (HashMap<String, VirtualPet>) shelter;
    }

    public void addPetToShelter(VirtualPet myPet) {
        shelter.put(myPet.getName(), myPet);
    }

// 
public class VirtualPet {

    private String name;
    private int hungerLevel;
    private int thirstLevel;
    private int boredomLevel;

    public String getName(){
        return name;
    }
    public int getHungerLevel(){
        return hungerLevel;
    }

    public int getThirstLevel(){
        return thirstLevel;
    }

    public int getBoredomLevel(){
        return boredomLevel;
    }

    public VirtualPet(String name, int hungerLevel, int thirstLevel, int boredomLevel) {
        this.name = name;
        this.hungerLevel = hungerLevel;
        this.thirstLevel = thirstLevel;
        this.boredomLevel = boredomLevel;

    }