You would expect a PriorityHeap to push down an item, but what if it actually does it upwards & is a PriorityQueue instead

PriorityQueueTest.java

package org.notmysock.test;

import static org.junit.jupiter.api.Assertions.*;

import java.util.PriorityQueue;

import org.junit.jupiter.api.Test;

class PriorityQueueTest {

  public static class EqObject implements Comparable {

    private final int n;

    public EqObject(int v) {
      this.n = v;
    }

    @Override
    public int compareTo(Object o) {
      return 0;
    }

    @Override
    public String toString() {
      return String.format("EqObject#%d", n);
    }
  }

  void cycle(PriorityQueue<EqObject> priorityQueue, int c) {
    EqObject horse = priorityQueue.poll();
    EqObject next = priorityQueue.peek();
    priorityQueue.add(horse);
    EqObject current = priorityQueue.peek();
    System.out.println(String.format(
        "Cycle%d - took out %s, top of heap %s and replaced to get %s again", c,
        horse, next, current));
  }

  @Test
  void test() {
    PriorityQueue<EqObject> priorityQueue = new PriorityQueue<EqObject>();
    EqObject span1 = new EqObject(1);
    EqObject span2 = new EqObject(2);
    EqObject span3 = new EqObject(3);

    priorityQueue.add(span1);
    priorityQueue.add(span2);
    priorityQueue.add(span3);

    for (int i = 0; i < 10; i++) {
      cycle(priorityQueue, i);
    }
  }
}