getMockBuilder(\Magento\Framework\App\Cache\Frontend\Pool::class) ->disableOriginalConstructor() ->getMock(); $poolMock->expects( $this->once() )->method( 'get' )->with( $this->equalTo($identifier) )->will( $this->returnArgument(0) ); $model = new \Magento\Framework\App\PageCache\Cache($poolMock); $this->assertInstanceOf(\Magento\Framework\App\PageCache\Cache::class, $model); } }