@Test
  public void testHashInner() {
    byte[] val = DUMMY;
    byte[] lchildval = hashed(val, 3, 3, 2);
    byte[] rchildval = hashed(val, 2, 2);
    byte[] fullval = hashed(val, 3, 3, 2, 2, 2);
    Range<Token> full = new Range<>(tok(-1), tok(-1));
    Range<Token> lchild = new Range<>(tok(-1), tok(4));
    Range<Token> rchild = new Range<>(tok(4), tok(-1));
    Range<Token> invalid = new Range<>(tok(1), tok(-1));

    // (zero,one] (one, two] (two,four] (four, six] (six, zero]
    mts.split(tok(4));
    mts.split(tok(2));
    mts.split(tok(6));
    mts.split(tok(1));
    assertNull(mts.hash(full));
    assertNull(mts.hash(lchild));
    assertNull(mts.hash(rchild));
    assertNull(mts.hash(invalid));

    // validate the range
    mts.get(tok(1)).hash(val);
    mts.get(tok(2)).hash(val);
    mts.get(tok(4)).hash(val);
    mts.get(tok(6)).hash(val);
    mts.get(tok(-1)).hash(val);

    assertHashEquals(fullval, mts.hash(full));
    assertHashEquals(lchildval, mts.hash(lchild));
    assertHashEquals(rchildval, mts.hash(rchild));
    assertNull(mts.hash(invalid));
  }
  @Test
  public void testHashDegenerate() {
    TOKEN_SCALE = new BigInteger("32");

    byte[] val = DUMMY;
    byte[] childfullval = hashed(val, 5, 5, 4);
    byte[] fullval = hashed(val, 5, 5, 4, 3, 2, 1);
    Range<Token> childfull = new Range<>(tok(-1), tok(4));
    Range<Token> full = new Range<>(tok(-1), tok(-1));
    Range<Token> invalid = new Range<>(tok(4), tok(-1));

    mts.split(tok(16));
    mts.split(tok(8));
    mts.split(tok(4));
    mts.split(tok(2));
    mts.split(tok(1));
    assertNull(mts.hash(full));
    assertNull(mts.hash(childfull));
    assertNull(mts.hash(invalid));

    // validate the range
    mts.get(tok(1)).hash(val);
    mts.get(tok(2)).hash(val);
    mts.get(tok(4)).hash(val);
    mts.get(tok(8)).hash(val);
    mts.get(tok(16)).hash(val);
    mts.get(tok(-1)).hash(val);

    assertHashEquals(fullval, mts.hash(full));
    assertHashEquals(childfullval, mts.hash(childfull));
    assertNull(mts.hash(invalid));
  }
  @Test
  public void testHashPartial() {
    byte[] val = DUMMY;
    byte[] leftval = hashed(val, 1, 1);
    byte[] partialval = hashed(val, 1);
    Range<Token> left = new Range<>(tok(-1), tok(4));
    Range<Token> partial = new Range<>(tok(2), tok(4));
    Range<Token> right = new Range<>(tok(4), tok(-1));
    Range<Token> linvalid = new Range<>(tok(1), tok(4));
    Range<Token> rinvalid = new Range<>(tok(4), tok(6));

    // (zero,two] (two,four] (four, zero]
    mts.split(tok(4));
    mts.split(tok(2));
    assertNull(mts.hash(left));
    assertNull(mts.hash(partial));
    assertNull(mts.hash(right));
    assertNull(mts.hash(linvalid));
    assertNull(mts.hash(rinvalid));

    // validate the range
    mts.get(tok(2)).hash(val);
    mts.get(tok(4)).hash(val);
    mts.get(tok(-1)).hash(val);

    assertHashEquals(leftval, mts.hash(left));
    assertHashEquals(partialval, mts.hash(partial));
    assertHashEquals(val, mts.hash(right));
    assertNull(mts.hash(linvalid));
    assertNull(mts.hash(rinvalid));
  }
  @Test
  public void testSplitLimitSize() {
    mts = new MerkleTrees(partitioner);

    mts.addMerkleTree(2, fullRange());

    assertTrue(mts.split(tok(4)));
    assertEquals(2, mts.size());

    // should fail to split above maxsize
    assertFalse(mts.split(tok(2)));
    assertEquals(2, mts.size());
    assertEquals(new Range<>(tok(4), tok(-1)), mts.get(tok(-1)));
    assertEquals(new Range<>(tok(-1), tok(4)), mts.get(tok(4)));
  }
  @Test
  public void testSplitLimitDepth() {
    mts = new MerkleTrees(partitioner);

    mts.addMerkleTree(Integer.MAX_VALUE, (byte) 2, fullRange());

    assertTrue(mts.split(tok(4)));
    assertTrue(mts.split(tok(2)));
    assertEquals(3, mts.size());

    // should fail to split below hashdepth
    assertFalse(mts.split(tok(1)));
    assertEquals(3, mts.size());
    assertEquals(new Range<>(tok(4), tok(-1)), mts.get(tok(-1)));
    assertEquals(new Range<>(tok(-1), tok(2)), mts.get(tok(2)));
    assertEquals(new Range<>(tok(2), tok(4)), mts.get(tok(4)));
  }
  @Test
  public void testSplit() {
    // split the range  (zero, zero] into:
    //  (zero,four], (four,six], (six,seven] and (seven, zero]
    mts.split(tok(4));
    mts.split(tok(6));
    mts.split(tok(7));

    assertEquals(4, mts.size());
    assertEquals(new Range<>(tok(7), tok(-1)), mts.get(tok(-1)));
    assertEquals(new Range<>(tok(-1), tok(4)), mts.get(tok(3)));
    assertEquals(new Range<>(tok(-1), tok(4)), mts.get(tok(4)));
    assertEquals(new Range<>(tok(4), tok(6)), mts.get(tok(6)));
    assertEquals(new Range<>(tok(6), tok(7)), mts.get(tok(7)));

    // check depths
    assertEquals((byte) 1, mts.get(tok(4)).depth);
    assertEquals((byte) 2, mts.get(tok(6)).depth);
    assertEquals((byte) 3, mts.get(tok(7)).depth);
    assertEquals((byte) 3, mts.get(tok(-1)).depth);

    try {
      mts.split(tok(-1));
      fail("Shouldn't be able to split outside the initial range.");
    } catch (AssertionError e) {
      // pass
    }
  }
  @Test
  public void testHashFull() {
    byte[] val = DUMMY;
    Range<Token> range = new Range<>(tok(-1), tok(-1));

    // (zero, zero]
    assertNull(mts.hash(range));

    // validate the range
    mts.get(tok(-1)).hash(val);

    assertHashEquals(val, mts.hash(range));
  }
  @Test
  public void testDifference() {
    int maxsize = 16;
    mts = new MerkleTrees(partitioner);
    mts.addMerkleTree(32, fullRange());

    MerkleTrees mts2 = new MerkleTrees(partitioner);
    mts2.addMerkleTree(32, fullRange());

    mts.init();
    mts2.init();

    // add dummy hashes to both trees
    for (TreeRange range : mts.invalids()) range.addAll(new HIterator(range.right));
    for (TreeRange range : mts2.invalids()) range.addAll(new HIterator(range.right));

    TreeRange leftmost = null;
    TreeRange middle = null;

    mts.maxsize(fullRange(), maxsize + 2); // give some room for splitting

    // split the leftmost
    Iterator<TreeRange> ranges = mts.invalids();
    leftmost = ranges.next();
    mts.split(leftmost.right);

    // set the hashes for the leaf of the created split
    middle = mts.get(leftmost.right);
    middle.hash("arbitrary!".getBytes());
    mts.get(partitioner.midpoint(leftmost.left, leftmost.right))
        .hash("even more arbitrary!".getBytes());

    // trees should disagree for (leftmost.left, middle.right]
    List<Range<Token>> diffs = MerkleTrees.difference(mts, mts2);
    assertEquals(diffs + " contains wrong number of differences:", 1, diffs.size());
    assertTrue(diffs.contains(new Range<>(leftmost.left, middle.right)));
  }