public function testRedPenBaseUrlCanBeChanged()
 {
     global $options;
     $options['redpen_base_url'] = 'http://localhost:8080/';
     $this->assertEquals('http://localhost:8080/', redpen_base_url());
     $this->assertEquals('http://localhost:8080/', $options['redpen_base_url']);
 }
<?php

/*
Plugin Name: RedPen Text Validator
Plugin URI: http://redpen.cc
Description: Validates posts with RedPen while editing.
Author: Anton Keks & Takahiko Ito
Version: 1.1.3
*/
$redpen_plugin_ver = '1.1.3';
$redpen_plugin_root = plugin_dir_url(__FILE__);
$redpen_base_url = redpen_base_url();
function redpen_base_url()
{
    $url = get_option('redpen_base_url');
    if (!$url) {
        $url = 'https://redpen.herokuapp.com/';
        update_option('redpen_base_url', $url);
    }
    return $url;
}
function redpen_head($page)
{
    if (strpos($page, 'post') !== 0) {
        return;
    }
    global $redpen_plugin_ver, $redpen_plugin_root, $redpen_base_url;
    wp_enqueue_script('redpen-api', $redpen_base_url . 'js/redpen.js', false, $redpen_plugin_ver);
    wp_enqueue_script('redpen-editor', $redpen_plugin_root . 'js/editor.js', false, $redpen_plugin_ver);
    wp_enqueue_script('redpen-plugin', $redpen_plugin_root . 'js/plugin.js', false, $redpen_plugin_ver);
    wp_enqueue_style('redpen-styles', $redpen_plugin_root . 'css/redpen.css', false, $redpen_plugin_ver);