'Test transform with an empty value.'

@pytest.mark.parametrize('val,    expected', [('', None), ('system', configtypes.SYSTEM_PROXY), ('none', QNetworkProxy(QNetworkProxy.NoProxy)), ('socks://example.com/', QNetworkProxy(QNetworkProxy.Socks5Proxy, 'example.com')), ('socks5://foo:bar@example.com:2323', QNetworkProxy(QNetworkProxy.Socks5Proxy, 'example.com', 2323, 'foo', 'bar'))])
def test_transform(self, klass, val, expected):

    actual = klass().transform(val)
    if isinstance(actual, QNetworkProxy):
        actual = QNetworkProxy(actual)
    assert (actual == expected)
