@Test public void testSkipCommand() throws Exception {
		String grammar =
			"lexer grammar L;\n"+
			"I : '0'..'9'+ {outStream.println(\"I\");} ;\n"+
			"WS : (' '|'\\n') -> skip ;";
		ExecutedState executedState = execLexer("L.g4", grammar, "L", "34 34");
		String expecting =
			"I\n" +
			"I\n" +
			"[@0,0:1='34',<1>,1:0]\n" +
			"[@1,3:4='34',<1>,1:3]\n" +
			"[@2,5:4='<EOF>',<-1>,1:5]\n";
		assertEquals(expecting, executedState.output);
	}
This is a regressing test for antlr/antlr4#469 "Not all internal lexer
rule actions are executed".
https://github.com/antlr/antlr4/issues/469
tool-testsuite/test/org/antlr/v4/test/tool/TestLexerActions.java