Is there a downside for using __init__(self) instead of setup(self) for a nose test class?

Question

Running nosetests -s for

class TestTemp():

    def __init__(self):
        print '__init__'
        self.even = 0

    def setup(self):
        print '__setup__'
        self.odd = 1

    def test_even(self):
        print 'test_even'
        even_number = 10
        assert even_number % 2 == self.even

    def test_odd(self):
        print 'test_odd'
        odd_number = 11
        assert odd_number % 2 == self.odd

prints out the following.

__init__
__init__
__setup__
test_even
.__setup__
test_odd
.

The test instances are created before tests are run, while setup runs right before the test.

For the general case, __init__() and setup() accomplish the same thing, but is there a downside for using __init__() instead of setup()? Or using both?

Answer 1

While __init__ may work as a replacement for setUp, you should stick to setUp because it is part of the stylized protocol for writing tests. It also has a counterpart, tearDown, which __init__ does not, as well as class- and module-level counterparts which __init__ does not.

Writing test classes is different than writing normal classes, so you should stick to the style used to write test classes.