@Test
  public void testPageFilter() throws IOException {
    String filterString = " PageFilter(4)";
    PageFilter pageFilter = doTestFilter(filterString, PageFilter.class);
    long pageSize = pageFilter.getPageSize();
    assertEquals(4, pageSize);

    filterString = " PageFilter('123')";
    try {
      doTestFilter(filterString, PageFilter.class);
      assertTrue(false);
    } catch (IllegalArgumentException e) {
      System.out.println("PageFilter needs an int as an argument");
    }
  }
This class tests ParseFilter.java It tests the entire work flow from when a string is given by
the user and how it is parsed to construct the corresponding Filter object
hbase-server/src/test/java/org/apache/hadoop/hbase/filter/TestParseFilter.java