public function testNormalizersTransformWithOptionalOption()
    {
        $this->resolver->setOptional(array(
            'foo'
        ));
        $this->resolver->setNormalizers(array(
            'foo' => function (Options $options, $value) {
                return strtoupper($value);
            },
        ));

        $this->assertEquals(array('foo' => 'BAR'), $this->resolver->resolve(array('foo' => 'bar')));

        $this->assertEquals(array(), $this->resolver->resolve(array()));
    }