### Question:
ColumnVisibility { public Node getParseTree() { return node; } ColumnVisibility();  ColumnVisibility(String expression);  ColumnVisibility(Text expression);  ColumnVisibility(byte[] expression); byte[] getExpression(); static Node normalize(Node root, byte[] expression); static Node normalize(Node root, byte[] expression, NodeComparator comparator); static void stringify(Node root, byte[] expression, StringBuilder out); byte[] flatten(); @Override String toString(); @Override boolean equals(Object obj); boolean equals(ColumnVisibility otherLe); @Override int hashCode(); Node getParseTree(); static String quote(String term); static byte[] quote(byte[] term);  }### Answer:
@Test public void testEmptyParseTreesAreEqual() { Comparator<Node> comparator = new NodeComparator(new byte[] {}); Node empty = new ColumnVisibility().getParseTree(); assertEquals(0, comparator.compare(empty, parse(""))); }