HeapSorter.java

public class HeapSorter {
  private int[] items;
  private int heapSize;
  private final int ROOT = 0;

  public HeapSorter(int[] items) {
    this.items = items;
    this.heapSize = 0;
  }

  public void sort() {
    for (int i = 0; i < items.length; i++) {
      add(items[i]);
    }

    for (int i = items.length - 1; i >= 0; i--) {
      items[i] = remove();
    }
  }

  public void add(int x) {
    // TODO
  }

  public void bubbleUp(int i) {
    // TODO
  }

  public void swap(int i, int j) {
    // TODO
  }

  public int parent(int i) {
    // TODO
    return -1;
  }

  public int remove() {
    // TODO
    return -1;
  }

  public void trickleDown(int i) {
    // TODO
  }

  public boolean hasLeft(int i) {
    // TODO
    return false;
  }

  public boolean hasRight(int i) {
    // TODO
    return false;
  }

  public int right(int i) {
    // TODO
    return -1;
  }

  public int left(int i) {
    // TODO
    return -1;
  }

}

HeapSorterTest.java

import org.junit.Before;
import org.junit.Test;

import java.util.Arrays;

import static org.junit.Assert.*;

public class HeapSorterTest {

  int[] items;
  HeapSorter hs;

  @Before
  public void setUp() throws Exception {
    items = new int[]{8, 12, 2, 10, 6, 4};
    hs = new HeapSorter(items);
  }

  @Test
  public void add() throws Exception {
    hs.add(8);
    assertEquals(
            Arrays.toString(new int[]{8, 12, 2, 10, 6, 4}),
            Arrays.toString(items)
    );
    hs.add(12);
    assertEquals(
            Arrays.toString(new int[]{12, 8, 2, 10, 6, 4}),
            Arrays.toString(items)
    );
  }

  @Test
  public void bubbleUp() throws Exception {
    hs.bubbleUp(1);
    assertEquals(
            Arrays.toString(new int[]{12, 8, 2, 10, 6, 4}),
            Arrays.toString(items)
    );
  }

  @Test
  public void parent() throws Exception {
    assertEquals(0, hs.parent(1));
  }

  @Test
  public void sort() throws Exception {
    hs.sort();
    assertEquals(
            Arrays.toString(new int[]{2, 4, 6, 8, 10, 12}),
            Arrays.toString(items)
    );
  }

  @Test
  public void swap() throws Exception {
    // TODO
    fail();
  }

  @Test
  public void remove() throws Exception {
    // TODO
    fail();
  }

  @Test
  public void trickleDown() throws Exception {
    // TODO
    fail();
  }

  @Test
  public void hasLeft() throws Exception {
    // TODO
    fail();
  }

  @Test
  public void hasRight() throws Exception {
    // TODO
    fail();
  }

  @Test
  public void right() throws Exception {
    // TODO
    fail();
  }

  @Test
  public void left() throws Exception {
    // TODO
    fail();
  }

}