### Question:
VersionHistory implements Serializable { public boolean isAncestorOf(VersionHistory child) { SnapshotIterator itParent = new SnapshotIterator(this); SnapshotIterator itChild = new SnapshotIterator(child); while (itParent.hasNext() && itChild.hasNext()) { if (!itParent.nextUuid().equals(itChild.nextUuid())) { return false; } int remaining = Math.min(itParent.remainingSameUuid(), itChild.remainingSameUuid()); UUID id = itParent.nextUuid(); itParent.advance(id, remaining); itChild.advance(id, remaining); } if (!itParent.hasNext()) { return true; } else { return false; } }  TreeMap<Integer, HistoryNode> calculateNodes(); int getVersionCount(); VersionHistoryEntry getLastEntry(); void addRestore(UUID streamId, int restoredSnapshotNr); void addVersion(UUID streamId); boolean isAncestorOf(VersionHistory child); @Override boolean equals(Object obj); @Override String toString();  }### Answer:
@Test public void testIsAncestorOf() throws Exception { VersionHistory h1 = new VersionHistory(); VersionHistory h2 = new VersionHistory(); UUID id1 = UUID.randomUUID(); UUID id2 = UUID.randomUUID(); assertTrue(h1.isAncestorOf(h2)); assertTrue(h2.isAncestorOf(h1)); h2.addVersion(id1); h2.addVersion(id1); assertTrue(h1.isAncestorOf(h2)); assertFalse(h2.isAncestorOf(h1)); h1.addVersion(id1); h1.addVersion(id1); assertTrue(h1.isAncestorOf(h2)); assertTrue(h2.isAncestorOf(h1)); h2.addVersion(id1); assertTrue(h1.isAncestorOf(h2)); assertFalse(h2.isAncestorOf(h1)); h1.addVersion(id2); h1.addVersion(id2); assertFalse(h1.isAncestorOf(h2)); assertFalse(h2.isAncestorOf(h1)); }