How to do unit testing on functions from another controller?

[eluser]Unknown[/eluser]
Hi, i would like to know how can i test my function in my controller?

my unit testing is one of the controller name test.php.
eg. http://localhost/demo/test

How can i test functions in 'customer' controller.
eg. i want to do a unit test for this function http://localhost/demo/customer/make_order

it is calling a controller from another controller which go against the MVC architecture?

but for unit testing purpose, any suggestion ways to test my functions in another controller?

thank you..