I have just stumbled on this while trying to write a JUnit test. Admittedly this is my first unit test in JUnit, but I do find the behaviour very puzzling.
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I was really surprised that some classes do behave like this in JUnit tests. I don't see any good reason for this in case of a simple DTO class like Point, but rather consider this as a nasty Easter egg which makes programmers' life harder. I would accept that methods like Draw etc. are mocked, as they can be heavily hardware-dependent, but such DTO's should not be mocked.
I'm still learning Android development, but the more such things I see the more I'm convinced that it is not a mature and well-thought framework.