Unit testing Firebase

I am trying to write unit tests for methods that load and add data from Firebase DB. I have not found any resources to help me with this. can someone point me to a resource or post a sample code? for example, this is my load method

    public ArrayList getGroceryData(final String type) {
   tempBuilder=new ArrayList<>();
     test=false;
    databaseReference.child("Tasks").child(type).addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if (dataSnapshot.exists()) {
                for (DataSnapshot d : dataSnapshot.getChildren()) {
                    tempBuilder.add(d.getValue(Task.class));
                }

                test=true;
               // Dashboard.populatefeed(tempBuilder);
            }
        }
        @Override
        public void onCancelled(DatabaseError databaseError) {

        }

    });

    while(!test);
    test=false;
    return tempBuilder;



}