assertNode example

->end()
                ->append(
                    $mailerNode = (new ArrayNodeDefinition('mailer'))
                        ->children()
                            ->booleanNode('enable')->end()
                            ->arrayNode('transports')->end()
                        ->end()
                )
            ->end()
        ;

        $this->assertNode('social_media_channels', ArrayNodeDefinition::class, $rootNode->find('social_media_channels'));
        $this->assertNode('enable', BooleanNodeDefinition::class, $rootNode->find('social_media_channels.enable'));
        $this->assertNode('twitter', ArrayNodeDefinition::class, $rootNode->find('social_media_channels.twitter'));
        $this->assertNode('facebook', ArrayNodeDefinition::class, $rootNode->find('social_media_channels.facebook'));
        $this->assertNode('instagram', ArrayNodeDefinition::class, $rootNode->find('social_media_channels.instagram'));
        $this->assertNode('enable', BooleanNodeDefinition::class, $rootNode->find('social_media_channels.instagram.enable'));
        $this->assertNode('accounts', ArrayNodeDefinition::class, $rootNode->find('social_media_channels.instagram.accounts'));

        $this->assertNode('enable', BooleanNodeDefinition::class, $mailerNode->find('enable'));
        $this->assertNode('transports', ArrayNodeDefinition::class, $mailerNode->find('transports'));
    }