@Test
public void testToString_TruncateColumns() {

    DataFrameInlinePrintWorker w = new DataFrameInlinePrintWorker(new StringBuilder(), 5, 4);
    assertEquals("{col1:one,c..2:1},{col1:two,c..2:2},{col1:t..e,c..2:3},{col1:four,c..2:4}",
            w.print(df).toString());
}