public function decrement(UnitTester $I)
{
$I->wantTo('Decrement counter by using Memory as cache backend');
$key = 'decrement';
$cache = new Memory(new Data(['lifetime' => 20]));
$I->setProtectedProperty($cache, '_data', [$key => 100]);
$I->assertEquals(99, $cache->decrement($key));
$I->assertEquals(96, $cache->decrement($key, 3));
$I->assertEquals(6, $cache->decrement($key, 90));
$I->assertEquals([$key => 6], $I->getProtectedProperty($cache, '_data'));
}