@Test public void testSubtractOfCompletelyCoveredRange() throws Exception {
        IntervalSet s = IntervalSet.of(10,20);
        IntervalSet s2 = IntervalSet.of(1,25);
        String expecting = "{}";
        String result = (s.subtract(s2)).toString();
        assertEquals(expecting, result);
    }
Public default constructor used by TestRig
tool-testsuite/test/org/antlr/v4/test/tool/TestIntervalSet.java