Laravel 5.1 testing env's always reads local configuration

I'm using sqlite in memory for testing in L5.1. I have 'default'=>'sqlite' in config/testing/database.php. env.testing has APP_ENV to testing. but when I run my tests, the tests hits the Mysql DB which apparently reads configurations from .env file instead of .env.testing. any ideas why this is causing? everything was smooth until upgraded to L5.1.