@Test public void testSize() throws Exception {
		IntervalSet s = IntervalSet.of(20,30);
		s.add(50,55);
		s.add(5,19);
		String expecting = "32";
		String result = String.valueOf(s.size());
		assertEquals(expecting, result);
	}
This case is responsible for antlr/antlr4#153.
https://github.com/antlr/antlr4/issues/153
tool-testsuite/test/org/antlr/v4/test/tool/TestIntervalSet.java