block = $objectManager->getObject(\Magento\Cms\Block\Page::class); $this->page = $objectManager->getObject(\Magento\Cms\Model\Page::class); $reflection = new \ReflectionClass($this->page); $reflectionProperty = $reflection->getProperty('_idFieldName'); $reflectionProperty->setAccessible(true); $reflectionProperty->setValue($this->page, 'page_id'); $this->page->setId(1); } protected function tearDown() { $this->block = null; } public function testGetIdentities() { $id = 1; $this->block->setPage($this->page); $this->assertEquals( [\Magento\Cms\Model\Page::CACHE_TAG . '_' . $id], $this->block->getIdentities() ); } }