public function testWithersReturnNewAModifiedInstance()
{
$parser = new ImpartialChainableParserAwareParser();
$newParser = $parser->withParser(new FakeParser());
$this->assertEquals(new ImpartialChainableParserAwareParser(), $parser);
$this->assertEquals(new ImpartialChainableParserAwareParser(new FakeParser()), $newParser);
}