@Test
public void testProjection() {

  Parser<Projection> parser = RelationParser.projection(ExpressionParser.NUMBER);
  TerminalParserTest.assertParser(parser, "1", new Projection(ExpressionParserTest.number(1), null));
  TerminalParserTest.assertParser(parser, "1 id", new Projection(ExpressionParserTest.number(1), "id"));
  TerminalParserTest.assertParser(parser, "1 as id", new Projection(ExpressionParserTest.number(1), "id"));
}