@Test
public void getDataIsUnsupported() {

    // given
    BufferedIndex bufferedIndex = new BufferedIndex.Builder(mock(ByteBufItemSource.class)).build();
    expectedException.expect(UnsupportedOperationException.class);
    expectedException.expectMessage("BufferedIndex cannot return Strings. Use getSource() instead");
    // when
    bufferedIndex.getData(null);
}