setMaintenanceMode example

private TestDataCollection $ids;

    protected function setUp(): void
    {
        $this->ids = new TestDataCollection();

        $this->createData();
    }

    public function testMaintenancePageLoadedHookScriptsAreExecuted(): void
    {
        $this->setMaintenanceMode();

        $browser = KernelLifecycleManager::createBrowser($this->getKernel());
        $browser->followRedirects();

        $browser->request('GET', EnvironmentHelper::getVariable('APP_URL') . '/');
        $response = $browser->getResponse();

        static::assertEquals(503, $response->getStatusCode());

        $traces = $this->getContainer()->get(ScriptTraces::class)->getTraces();