/**
     * @covers WPSEO_Twitter::twitter
     */
    public function test_twitter()
    {
        $post_id = $this->factory->post->create(array('post_title' => 'Twitter Test Post', 'post_excerpt' => 'Twitter Test Excerpt', 'post_type' => 'post', 'post_status' => 'publish'));
        $this->go_to(get_permalink($post_id));
        self::$class_instance->twitter();
        $expected = '<meta name="twitter:card" content="summary"/>
<meta name="twitter:description" content="Twitter Test Excerpt"/>
<meta name="twitter:title" content="Twitter Test Post - Test Blog"/>
<meta name="twitter:domain" content="Test Blog"/>
';
        $this->expectOutput($expected);
    }