@Test
public void testToConcreteFilters() throws IOException {

  FiltersCounter counter = new FiltersCounter();
  ThemisCpUtil.processFilters(null, counter);
  Assert.assertEquals(0, counter.concreteFilterCount);
  counter = new FiltersCounter();
  ThemisCpUtil.processFilters(new ColumnRangeFilter(), counter);
  Assert.assertEquals(1, counter.concreteFilterCount);
  counter = new FiltersCounter();
  FilterList filterList = new FilterList();
  filterList.addFilter(new ColumnRangeFilter());
  filterList.addFilter(new ColumnCountGetFilter());
  ThemisCpUtil.processFilters(filterList, counter);
  Assert.assertEquals(2, counter.concreteFilterCount);
  // test process filterlist operator
  counter = new ConcreteFiltersCounter();
  ThemisCpUtil.processFilters(new ColumnRangeFilter(), counter);
  Assert.assertEquals(1, counter.concreteFilterCount);
  counter = new ConcreteFiltersCounter();
  ThemisCpUtil.processFilters(filterList, counter);
  Assert.assertEquals(0, counter.concreteFilterCount);
}