class DataFrameAsserts {

    public DataFrameAsserts expectHeight(int expectedHeight) {
        assertEquals(expectedHeight, df.height(), "Unexpected DataFrame height");
        return this;
    }

    public  DataFrameAsserts(DataFrame df, Index expectedColumns);
    public  DataFrameAsserts(DataFrame df, List<String> expectedColumns);
    public  DataFrameAsserts(DataFrame df, String... expectedColumns);

}