public function testSave()
{
$item = $this->getMockBuilder(CacheItemInterface::class)->getMock();
$prefix = 'ns';
$returnValue = true;
$stub = $this->getHierarchyCacheStub();
$stub->expects($this->once())->method('save')->with($item)->willReturn($returnValue);
$pool = new PrefixedCachePool($stub, $prefix);
$this->assertEquals($returnValue, $pool->save($item));
}