@Test
public void customColumnTypes() {
GenericColumnId fileColumnId = new GenericColumnId("File", new ColumnType<>("File", GenericColumnId.class));
File fileA = new File("/path/to/a.txt");
File fileB = new File("/path/to/b.txt");
GenericColumn<File, GenericColumnId> fileColumn = GenericColumn.ofAll(fileColumnId, fileA, fileB);
DataFrame df = DataFrame.of(fileColumn);
assertEquals(2, df.getRowCount());
assertEquals(1, df.getColumnCount());
GenericColumn<File, GenericColumnId> column = df.getColumn(fileColumnId);
assertEquals(fileColumn, column);
File fileValue = df.getValueAt(1, fileColumnId);
assertEquals(fileB, fileValue);
}