Unit testing by definition is testing of individual units where a unit is the smallest testable part of an application for example a class method in isolation. What it means is, we have to ideally test just the logic within the method and not the logic of supporting classes or libraries being used in the current method.
Now we can do this through an automated tool like junit/testNG/nunit/flexunit etc by creating stubs and even more often now mock objects which are not real objects but still mimic their behavior making it possible to unit-test functionality of a single class without actually calling underlying or collaborating classes. How is it possible manually?
The answer is NO, it is not and thus any form of manual unit testing is actually integration testing.
