strange permission issue with nosetests

[Mr.SpOOn]

Hi,
I'm trying the nose testing package. I've just started reading the
tutorial and I had a problem with the first simple example.

This is the test:

def test_b():
    assert 'b' == 'b'

In the same directory I gave the command nosetests and it runs the test.

Then I try with nosetests -v, but it just says this:

----------------------------------------------------------------------
Ran 0 tests in 0.003s

OK

I thought because I didn't change anything in the file, don't know.
Tried to change, but nothing. I moved on and wrote another test,
inside a class, but nothing. It just doesn't run tests.

Searching on google I found this: http://www.siafoo.net/article/61
He had the same issue and said to change permission of the file to 664.

I tried and it worked.
Is that normal? Why does it happen?