@Test public void testDoubleQuoteInTwoStringLiterals() {
		String grammar =
			"lexer grammar A;\n" +
			"STRING : '\\\"' '\\\"' 'x' ;";
		String expected =
			"error(" + ErrorType.INVALID_ESCAPE_SEQUENCE.code + "): A.g4:2:10: invalid escape sequence \\\"\n"+
			"error(" + ErrorType.INVALID_ESCAPE_SEQUENCE.code + "): A.g4:2:15: invalid escape sequence \\\"\n";

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

		testErrors(pair, true);
	}
This is a regression test for https://github.com/antlr/antlr4/issues/1815
"Null ptr exception in SqlBase.g4"
tool-testsuite/test/org/antlr/v4/test/tool/TestToolSyntaxErrors.java