@Test public void testSubtractOfOverlappingRangeFromLeft() throws Exception {
		IntervalSet s = IntervalSet.of(10,20);
		IntervalSet s2 = IntervalSet.of(5,11);
		String expecting = "{12..20}";
        String result = (s.subtract(s2)).toString();
        assertEquals(expecting, result);

        IntervalSet s3 = IntervalSet.of(5,10);
        expecting = "{11..20}";
        result = (s.subtract(s3)).toString();
        assertEquals(expecting, result);
    }
Public default constructor used by TestRig
tool-testsuite/test/org/antlr/v4/test/tool/TestIntervalSet.java