@Test
public void testToRowColumn() {

  Assert.assertEquals(RowColumn.EMPTY, SpanUtil.toRowColumn(null));
  Assert.assertEquals(new RowColumn("row"), SpanUtil.toRowColumn(new Key("row")));
  Assert.assertEquals(new RowColumn("row", new Column("cf")),
      SpanUtil.toRowColumn(new Key("row", "cf")));
  Assert.assertEquals(new RowColumn("row", new Column("cf", "cq")),
      SpanUtil.toRowColumn(new Key("row", "cf", "cq")));
  Assert.assertEquals(new RowColumn("row", new Column("cf", "cq", "cv")),
      SpanUtil.toRowColumn(new Key("row", "cf", "cq", "cv")));
}