@Test public void testIsolatedLeftRecursiveRuleRef() throws Exception {
		String grammar =
			"grammar T;\n" +
			"a : a | b ;\n" +
			"b : 'B' ;\n";
		String expected =
			"error(" + ErrorType.NONCONFORMING_LR_RULE.code + "): T.g4:2:0: rule a is left recursive but doesn't conform to a pattern ANTLR can handle\n";
		testErrors(new String[]{grammar, expected}, false);
	}
Reproduces https://github.com/antlr/antlr4/issues/822
tool-testsuite/test/org/antlr/v4/test/tool/TestLeftRecursionToolIssues.java