@Test
  public void testUpdateDigest() throws Exception {
    MessageDigest digest1 = MessageDigest.getInstance("md5");
    MessageDigest digest2 = MessageDigest.getInstance("md5");

    CounterContext.ContextState state = CounterContext.ContextState.allocate(4, 2);
    state.writeElement(NodeId.fromInt(1), 4L, 4L);
    state.writeElement(NodeId.fromInt(2), 4L, 4L, true);
    state.writeElement(NodeId.fromInt(3), 4L, 4L);
    state.writeElement(NodeId.fromInt(4), 4L, 4L, true);

    CounterColumn original = new CounterColumn(ByteBufferUtil.bytes("x"), state.context, 1L);
    CounterColumn cleared =
        new CounterColumn(ByteBufferUtil.bytes("x"), cc.clearAllDelta(state.context), 1L);

    original.updateDigest(digest1);
    cleared.updateDigest(digest2);

    assert Arrays.equals(digest1.digest(), digest2.digest());
  }
  @Test
  public void testCreate() throws UnknownHostException {
    long delta = 3L;
    CounterUpdateColumn cuc = new CounterUpdateColumn(ByteBufferUtil.bytes("x"), delta, 1L);
    CounterColumn column = cuc.localCopy(Table.open("Keyspace5").getColumnFamilyStore("Counter1"));

    assert delta == column.total();
    assert 1 == column.value().getShort(0);
    assert 0 == column.value().getShort(2);
    assert NodeId.wrap(column.value(), 4).isLocalId();
    assert 1L == column.value().getLong(4 + 0 * stepLength + idLength);
    assert delta == column.value().getLong(4 + 0 * stepLength + idLength + clockLength);
  }
  @Test
  public void testSerializeDeserialize() throws IOException {
    CounterContext.ContextState state = CounterContext.ContextState.allocate(4, 2);
    state.writeElement(NodeId.fromInt(1), 4L, 4L);
    state.writeElement(NodeId.fromInt(2), 4L, 4L, true);
    state.writeElement(NodeId.fromInt(3), 4L, 4L);
    state.writeElement(NodeId.fromInt(4), 4L, 4L, true);

    CounterColumn original = new CounterColumn(ByteBufferUtil.bytes("x"), state.context, 1L);
    DataOutputBuffer bufOut = new DataOutputBuffer();
    Column.serializer().serialize(original, bufOut);
    byte[] serialized = bufOut.getData();

    ByteArrayInputStream bufIn = new ByteArrayInputStream(serialized, 0, serialized.length);
    CounterColumn deserialized =
        (CounterColumn) Column.serializer().deserialize(new DataInputStream(bufIn));
    assert original.equals(deserialized);

    bufIn = new ByteArrayInputStream(serialized, 0, serialized.length);
    CounterColumn deserializedOnRemote =
        (CounterColumn) Column.serializer().deserialize(new DataInputStream(bufIn), null, true);
    assert deserializedOnRemote.name().equals(original.name());
    assert deserializedOnRemote.total() == original.total();
    assert deserializedOnRemote.value().equals(cc.clearAllDelta(original.value()));
    assert deserializedOnRemote.timestamp() == deserialized.timestamp();
    assert deserializedOnRemote.timestampOfLastDelete() == deserialized.timestampOfLastDelete();
  }
  @Test
  public void testDiff() throws UnknownHostException {
    ContextState left;
    ContextState right;

    CounterColumn leftCol;
    CounterColumn rightCol;

    // timestamp
    leftCol = new CounterColumn(ByteBufferUtil.bytes("x"), 0, 1L);
    rightCol = new CounterColumn(ByteBufferUtil.bytes("x"), 0, 2L);

    assert rightCol == leftCol.diff(rightCol);
    assert null == rightCol.diff(leftCol);

    // timestampOfLastDelete
    leftCol = new CounterColumn(ByteBufferUtil.bytes("x"), 0, 1L, 1L);
    rightCol = new CounterColumn(ByteBufferUtil.bytes("x"), 0, 1L, 2L);

    assert rightCol == leftCol.diff(rightCol);
    assert null == rightCol.diff(leftCol);

    // equality: equal nodes, all counts same
    left = ContextState.allocate(3, 0);
    left.writeElement(NodeId.fromInt(3), 3L, 0L);
    left.writeElement(NodeId.fromInt(6), 2L, 0L);
    left.writeElement(NodeId.fromInt(9), 1L, 0L);
    right = new ContextState(ByteBufferUtil.clone(left.context), 2);

    leftCol = new CounterColumn(ByteBufferUtil.bytes("x"), left.context, 1L);
    rightCol = new CounterColumn(ByteBufferUtil.bytes("x"), right.context, 1L);
    assert null == leftCol.diff(rightCol);

    // greater than: left has superset of nodes (counts equal)
    left = ContextState.allocate(4, 0);
    left.writeElement(NodeId.fromInt(3), 3L, 0L);
    left.writeElement(NodeId.fromInt(6), 2L, 0L);
    left.writeElement(NodeId.fromInt(9), 1L, 0L);
    left.writeElement(NodeId.fromInt(12), 0L, 0L);

    right = ContextState.allocate(3, 0);
    right.writeElement(NodeId.fromInt(3), 3L, 0L);
    right.writeElement(NodeId.fromInt(6), 2L, 0L);
    right.writeElement(NodeId.fromInt(9), 1L, 0L);

    leftCol = new CounterColumn(ByteBufferUtil.bytes("x"), left.context, 1L);
    rightCol = new CounterColumn(ByteBufferUtil.bytes("x"), right.context, 1L);
    assert null == leftCol.diff(rightCol);

    // less than: right has subset of nodes (counts equal)
    assert leftCol == rightCol.diff(leftCol);

    // disjoint: right and left have disjoint node sets
    left = ContextState.allocate(3, 0);
    left.writeElement(NodeId.fromInt(3), 1L, 0L);
    left.writeElement(NodeId.fromInt(4), 1L, 0L);
    left.writeElement(NodeId.fromInt(9), 1L, 0L);

    right = ContextState.allocate(3, 0);
    right.writeElement(NodeId.fromInt(3), 1L, 0L);
    right.writeElement(NodeId.fromInt(6), 1L, 0L);
    right.writeElement(NodeId.fromInt(9), 1L, 0L);

    leftCol = new CounterColumn(ByteBufferUtil.bytes("x"), left.context, 1L);
    rightCol = new CounterColumn(ByteBufferUtil.bytes("x"), right.context, 1L);
    assert rightCol == leftCol.diff(rightCol);
    assert leftCol == rightCol.diff(leftCol);
  }