Teste JUnit na classe com firebase

eu estou tentandoJUnit teste esta classe:

public class WeekListActivity extends AppCompatActivity implements AdapterView.OnItemClickListener {

    private ArrayList<String> weekList = new ArrayList<>();
    private ArrayAdapter<String> adapter;


    ListView weekListView;
    Button AddWeekButton;
    EditText InsertWeekEditText;
    String weekNumber;
    String subjectName;
    String subjectCode;
    User user;

    DatabaseReference mDatabase;
    DatabaseReference mRef;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_week_list);
        FirebaseApp.initializeApp(this);

        FirebaseAuth firebaseAuth = FirebaseAuth.getInstance();
        FirebaseUser firebaseUser = firebaseAuth.getCurrentUser();

        Intent moveToDetailIntent = this.getIntent();
        subjectName = moveToDetailIntent.getExtras().getString("Subject");
        subjectCode = moveToDetailIntent.getExtras().getString("Fagkode");

        mDatabase = FirebaseDatabase.getInstance().getReference().child("Studentfag").child(subjectCode).child("Week");
        mRef = FirebaseDatabase.getInstance().getReference().child("Users").child(firebaseUser.getUid()).child("User info");

        weekListView = (ListView) findViewById(R.id.WeekListView);
        AddWeekButton = (Button) findViewById(R.id.AddWeekButton);
        InsertWeekEditText = (EditText) findViewById(R.id.InsertWeek);

        String userID = firebaseUser.getUid();
        mRef.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                user = dataSnapshot.getValue(User.class);
                if (user.isStudent){
                    View a = weekListView;
                    a.setMinimumHeight(80);
                    View b = AddWeekButton;
                    b.setVisibility(View.GONE);
                    View c = InsertWeekEditText;
                    c.setVisibility(View.GONE);
                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

        adapter = new ArrayAdapter<String>(getBaseContext(), android.R.layout.simple_list_item_1, weekList);
        weekListView.setAdapter(adapter);
        weekListView.setOnItemClickListener(this);
        AddWeekButton.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                weekNumber= InsertWeekEditText.getText().toString();
                mDatabase.child(weekNumber).child("id").setValue(weekNumber);
            }
        });

        mDatabase.addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {
                String week = dataSnapshot.getKey().toString();
                    weekList.add("Week: " + week);
                    adapter.notifyDataSetChanged();
                }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {

            }

            //Urelevante metoder for oss.
            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String s) {}
            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String s) {}
            @Override
            public void onCancelled(DatabaseError databaseError) {}
        });

    }

O problema é que, quando eu construo uma nova atividade no meu método de instalação, ela reclama porque esta frase:

mRef = FirebaseDatabase.getInstance().getReference().child("Users").child(firebaseUser.getUid()).child("User info");

não é capaz de construir quando não temos um usuário do firebase. Portanto, tentei zombar de um usuário da base de firmas na minha classe de teste. A questão é: como posso dizer à classe que ele deve usar o firebaseuseronCreate? Existe uma maneira de "enviar" o objeto zombado? Obrigado!

O início do meu método de instalação:

  @Before
public void setUp() throws Exception {

    Intent i = new Intent();
    i.putExtra("Subject", "Matematikk 1");
    i.putExtra("Fagkode", "TMA4100");

    FirebaseUser mockFirebaseUser = mock(FirebaseUser.class);
    when(mockFirebaseUser.getUid()).thenReturn("uTZpVPPz8NT2LOvP4ufjs1L6r3P2");

    Activity activity = Robolectric.buildActivity(WeekListActivity.class).withIntent(i).create().get();

}

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