Contao\CoreBundle\Test\EventListener\MergeHttpHeadersListenerTest::testMultiValueHeadersAreNotOverriden PHP Method

    public function testMultiValueHeadersAreNotOverriden()
    {
        $response = new Response();
        $response->headers->set('Set-Cookie', 'content');
        $responseEvent = new FilterResponseEvent($this->mockKernel(), new Request(), HttpKernelInterface::MASTER_REQUEST, $response);
        /** @var ContaoFrameworkInterface|\PHPUnit_Framework_MockObject_MockObject $framework */
        $framework = $this->getMock('Contao\\CoreBundle\\Framework\\ContaoFrameworkInterface');
        $framework->expects($this->once())->method('isInitialized')->willReturn(true);
        $listener = new MergeHttpHeadersListener($framework);
        $listener->setHeaders(['set-cookie: new-content']);
        // test a lower-case key here
        $listener->onKernelResponse($responseEvent);
        $response = $responseEvent->getResponse();
        $this->assertTrue($response->headers->has('Set-Cookie'));
        $allHeaders = $response->headers->get('Set-Cookie', null, false);
        $this->assertSame('content', $allHeaders[0]);
        $this->assertSame('new-content', $allHeaders[1]);
    }