@Test public void testEpsilonNestedClosureAnalysis() {
		String grammar =
			"grammar T;\n"+
			"s : (a a)* ;\n"+
			"a : 'foo'* ;\n";
		String expected =
			"error(" + ErrorType.EPSILON_CLOSURE.code + "): T.g4:2:0: rule s contains a closure with at least one alternative that can match an empty string\n";

		String[] pair = new String[] {
			grammar,
			expected
		};

		testErrors(pair, true);
	}
This is a regression test for antlr/antlr4#190
"NullPointerException building lexer grammar using bogus 'token' action"
https://github.com/antlr/antlr4/issues/190
tool-testsuite/test/org/antlr/v4/test/tool/TestToolSyntaxErrors.java