public function flushByTagSanitizesTagsForCacheFrontend($tag, $sanitizedTag)
{
$mockCache = $this->getMockBuilder(StringFrontend::class)->disableOriginalConstructor()->getMock();
$mockCache->expects($this->once())->method('flushByTag')->with($sanitizedTag);
$contentCache = new ContentCache();
$this->inject($contentCache, 'cache', $mockCache);
$contentCache->flushByTag($tag);
}