### Question:
DeltaEncoder { static List<Integer> doubleDeltaEncode(List<Integer> list) { if (list == null) { return null; } ArrayList<Integer> result = new ArrayList<>(); if (list.isEmpty()) { return result; } Iterator<Integer> it = list.iterator(); Integer prevLat = it.next(); Integer prevLon = it.next(); Integer prevLatDelta = Integer.valueOf(0); Integer prevLonDelta = Integer.valueOf(0); result.add(prevLat); result.add(prevLon); while (it.hasNext()) { Integer currentLat = it.next(); Integer currentLon = it.next(); Integer deltaLat = Integer.valueOf(currentLat.intValue() - prevLat.intValue()); Integer deltaLon = Integer.valueOf(currentLon.intValue() - prevLon.intValue()); result.add(Integer.valueOf(deltaLat.intValue() - prevLatDelta.intValue())); result.add(Integer.valueOf(deltaLon.intValue() - prevLonDelta.intValue())); prevLat = currentLat; prevLon = currentLon; prevLatDelta = deltaLat; prevLonDelta = deltaLon; } return result; } private  DeltaEncoder(); static List<WayDataBlock> encode(List<WayDataBlock> blocks, Encoding encoding); static int simulateSerialization(List<WayDataBlock> blocks);  }### Answer:
@Test public void testDoubleDeltaEncode() { List<Integer> ddeltaEncoded = DeltaEncoder.doubleDeltaEncode(this.mockCoordinates); Assert.assertEquals(Integer.valueOf(52000000), ddeltaEncoded.get(0)); Assert.assertEquals(Integer.valueOf(13000000), ddeltaEncoded.get(1)); Assert.assertEquals(Integer.valueOf(100), ddeltaEncoded.get(2)); Assert.assertEquals(Integer.valueOf(100), ddeltaEncoded.get(3)); Assert.assertEquals(Integer.valueOf(300), ddeltaEncoded.get(4)); Assert.assertEquals(Integer.valueOf(300), ddeltaEncoded.get(5)); Assert.assertEquals(Integer.valueOf(-500), ddeltaEncoded.get(6)); Assert.assertEquals(Integer.valueOf(-500), ddeltaEncoded.get(7)); Assert.assertEquals(Integer.valueOf(500), ddeltaEncoded.get(8)); Assert.assertEquals(Integer.valueOf(500), ddeltaEncoded.get(9)); Assert.assertEquals(Integer.valueOf(-200), ddeltaEncoded.get(10)); Assert.assertEquals(Integer.valueOf(-200), ddeltaEncoded.get(11)); }