public function testSetETagGenerator()
 {
     $testGenerator = $this->prophesize(ETagGeneratorInterface::class);
     $testGenerator->generate(Argument::any(), Argument::any())->willReturn('generated');
     $httpCacheListener = new HttpCacheListener($testGenerator->reveal());
     $httpCacheListener->setCacheConfig(['etag' => ['override' => true, 'generator' => 'test-etag-generator']]);
     $response = new HttpResponse();
     $headers = $response->getHeaders();
     $httpCacheListener->setETag(new HttpRequest(), $response);
     $this->assertSame(['Etag' => 'generated'], $headers->toArray());
 }