Hi nysus,

Testing private methods is perfectly fine. As you say, often it's advantageous to test as small a unit as possible.

If you have a class that has private methods, then having a test file that tests the private methods of that class is normal. On the other hand, what I personally would try to avoid is accessing other classes' private methods from tests - it's often a sign that your API might need some refactoring (like providing a public accessor for the data or even that a restructuring of the classes might help).

Hope this helps,
-- Hauke D