Laravel overrides phpunit.xml environment variables

Hello guys,

I am currently facing a strange problem, which happened to me for the first time after working with laravel for a year and a half now.

I have been doing TDD with PHPUnit for a quite some time now and I have always declared the configuration variables, which will be used by the test environment, in phpunit.xml like so:

    ....
    <php>
        <env name="APP_ENV" value="testing"/>
        <env name="CACHE_DRIVER" value="array"/>
        <env name="SESSION_DRIVER" value="array"/>
        <env name="QUEUE_DRIVER" value="sync"/>
        <env name="DB_DEFAULT" value="sqlite_testing" />
    </php>
    ....

However now these variables do not seem to take any effect. They are completely overridden by the ones, declared in the .env file. Because of this I was forced to populate the configuration files with ugly statements like this one (config/database.php):

'default' => $app->environment() == 'testing' ? 'sqlite_testing' : env('DB_CONNECTION', 'mysql'),

I am currently running Laravel 5.1 on the latest homestead. The problem is not from homestead in my opinion since I updated it a couple of days ago and the problem still occurs.

Does anyone know how to fix this annoying problem?

Update: I spent a lot of time searching if someone else had faced the same issue but unluckily could not find any information.