ZF2 - Mocking service requested in Module.php

I am trying to test a controller of my ZF2 application. Suppose this controller is in my A module.

In the onBootstrap method of the Module.php of the module A I am using the service manager to retrieve a service of another module, say B, that I am not loading.

How can set a mock of the requested service in the service manager? Mind that I can not use $this->getApplicationServiceLocator() to do this in my test, since this is already calling the Module.onBootstrap method of my A module.

To post some code, this is what I am doing at the moment

bootstrap.php

namespace Application;

use Zend\Mvc\Service\ServiceManagerConfig;
use Zend\ServiceManager\ServiceManager;
use RuntimeException;

class Bootstrap
{
    protected static $serviceManager;

    public static function init()
    {
        $modulePath = static::findParentPath('module');
        $vendorPath = static::findParentPath('vendor');

        if (is_readable($vendorPath . '/autoload.php')) {
            $loader = include $vendorPath . '/autoload.php';
        } else {
            throw new RuntimeException('Cannot locate autoload.php');
        }

        $config = [
            'modules' => [
                'Application',
            ],
            'module_listener_options' => [
                'module_paths' => [
                    $modulePath,
                    $vendorPath
                ]
            ]
        ];

        $serviceManager = new ServiceManager(new ServiceManagerConfig());
        $serviceManager->setService('ApplicationConfig', $config);
        $serviceManager->get('ModuleManager')->loadModules();
        static::$serviceManager = $serviceManager;
    }

    protected static function findParentPath($path)
    {
        $dir = __DIR__;
        $previousDir = '.';
        while (!is_dir($dir . '/' . $path)) {
            $dir = dirname($dir);
            if ($previousDir === $dir) {
                return false;
            }
            $previousDir = $dir;
        }
        return $dir . '/' . $path;
    }

    public static function getServiceManager()
    {
        return static::$serviceManager;
    }
}

Bootstrap::init();

my actual test class

namespace Application\Functional;

use Application\Bootstrap;

use Zend\Test\PHPUnit\Controller\AbstractHttpControllerTestCase;

class ValidateCustomerRegistrationTest extends AbstractHttpControllerTestCase
{
    public function setUp()
    {
        $serviceManager = Bootstrap::getServiceManager();
        $applicationConfig = $serviceManager->get('ApplicationConfig');

        $this->setApplicationConfig($applicationConfig);
        parent::setUp();
    }

    public function testRegisterValidUserWithOnlyEquomobiliData()
    {
        $this->getApplicationServiceLocator();
    }
}

Module.php simplified

namespace Application

Class Module { public function onBootstrap(MvcEvent $e) { $serviceManager = $e->getApplication()->getServiceManager(); $service = $serviceManager->get('Service\From\Other\Module'); } }