public function testExtendWithCacheMock()
 {
     $definitions = $this->getMock('Magento\\Framework\\ObjectManager\\DefinitionInterface');
     $definitions->expects($this->once())->method('getClasses')->will($this->returnValue(['FooType']));
     $cache = $this->getMock('Magento\\Framework\\ObjectManager\\ConfigCacheInterface');
     $cache->expects($this->once())->method('get')->will($this->returnValue(false));
     $config = new Config(null, $definitions);
     $config->setCache($cache);
     $this->_assertFooTypeArguments($config);
 }