public function testWithersReturnNewModifiedObject()
{
$bag = new ParameterBag(['foo' => 'bar']);
$newBag = $bag->with(new Parameter('ping', 'pong'));
$this->assertEquals(new ParameterBag(['foo' => 'bar']), $bag);
$this->assertEquals(new ParameterBag(['foo' => 'bar', 'ping' => 'pong']), $newBag);
}