如何对依赖常量的工厂类进行单元测试

所以我有这个工厂类实现Zend'ServiceManager'FactoryInterface:

class GatewayFactory implements FactoryInterface
{
    public function createService(ServiceLocatorInterface $serviceLocator)
    {
        $config = new Config($serviceLocator->get('ApplicationConfig'));
        if ('phpunit' === APPLICATION_ENV) {
            return new Gateway($config, new Mock());
        }
        return new Gateway($config);
    }
}

它总是返回网关实例，但是当APPLICATION_ENV常量为"phpunit"时，会添加一个模拟适配器作为第二个参数。

我正在使用以下配置运行单元测试:

<?xml version="1.0" encoding="UTF-8"?>
<phpunit bootstrap="tests/unit/Bootstrap.php" colors="true" backupGlobals="false" backupStaticAttributes="false" syntaxCheck="false">
    <testsuites>
        <testsuite name="mysuite">
            <directory suffix="Test.php">tests/unit</directory>
        </testsuite>
    </testsuites>
    <php>
        <const name="APPLICATION_ENV" value="phpunit"/>
    </php>
</phpunit>

因此APPLICATION_ENV被设置为"phpunit"。当常数不同时，我如何编写测试?

我可以测试if条件，但我不知道如何测试不属于if条件的情况:

class GatewayFactoryTest extends PHPUnit_Framework_TestCase
{
    public function testCreateServiceReturnsGatewayWithMockAdapterWhenApplicationEnvIsPhpunit()
    {
        $factory = new GatewayFactory();
        $gateway = $factory->createService(Bootstrap::getServiceManager());
        $this->assertInstanceOf('Mock', $gateway->getAdapter());
    }
    public function testCreateServiceReturnsGatewayWithSockerAdapterWhenApplicationEnvIsNotPhpunit()
    {
        // TODO HOW TO DO THIS?
    }
}