Test display extenders.
public function testDisplayExtenders() {
config('views.settings')
->set('display_extenders', array(
'display_extender_test',
))
->save();
$this
->assertEqual(count(views_get_enabled_display_extenders()), 1, 'Make sure that there is only one enabled display extender.');
$view = views_get_view('test_view');
$view
->initDisplay();
$this
->assertEqual(count($view->display_handler->extender), 1, 'Make sure that only one extender is initialized.');
$display_extender = $view->display_handler->extender['display_extender_test'];
$this
->assertTrue($display_extender instanceof \Drupal\views_test_data\Plugin\views\display_extender\DisplayExtenderTest, 'Make sure the right class got initialized.');
$view
->preExecute();
$this
->assertTrue($display_extender->testState['pre_execute'], 'Make sure the display extender was able to react on preExecute.');
$view
->execute();
$this
->assertTrue($display_extender->testState['query'], 'Make sure the display extender was able to react on query.');
}