@Test
public void testSplitByFileId_oneFile_secondary() {

    final List<SamplingPoint> points = new ArrayList<>();
    points.add(createSamplingPointWithSecondaryReference(21));
    points.add(createSamplingPointWithSecondaryReference(21));
    points.add(createSamplingPointWithSecondaryReference(21));
    final Map<Integer, List<SamplingPoint>> listByFileId = DirtySubsceneRemover.splitByFileId(points, false);
    assertEquals(1, listByFileId.size());
    final List<SamplingPoint> fileList = listByFileId.get(21);
    assertNotNull(fileList);
    assertEquals(3, fileList.size());
}