testing twig with phpunit

I want to implement some unit tests with Twig and PHPUnit(both installed with composer, with slim/views added). But when I try to test a template generation, it blocks at . But the templates works fine when I test it on the navigator, without phpunit.

here is the error message :

Twig_Error_Runtime: An exception has been thrown during the rendering of a template 
("Undefined index: REQUEST_METHOD") in "application/General.twig" at line 21.