Piwik\AssetManager::getCompiledBaseCss PHP Method

    public function getCompiledBaseCss()
    {
        $mergedAsset = new InMemoryUIAsset();
        $assetMerger = new StylesheetUIAssetMerger($mergedAsset, $this->minimalStylesheetFetcher, $this->cacheBuster);
        $assetMerger->generateFile();
        return $mergedAsset;
    }

 /**
  * @group Core
  */
 public function test_getCompiledBaseCss()
 {
     $this->setStylesheetCacheBuster(self::FIRST_CACHE_BUSTER_SS);
     $staticStylesheetList = array_merge($this->getCorePluginStylesheetFiles(), array($this->getCoreThemeStylesheet()));
     $minimalAssetFetcher = new StaticUIAssetFetcher(array_reverse($staticStylesheetList), $staticStylesheetList, $this->getCoreTheme());
     $this->assetManager->setMinimalStylesheetFetcher($minimalAssetFetcher);
     $this->mergedAsset = $this->assetManager->getCompiledBaseCss();
     $this->validateMergedStylesheet();
 }