Want to call a method only once for unittest.TestCase--but not sure how?

[Oltmans]

Hello fellow python hackers,

I'm not an expert when it comes to Python and I'm totally stuck in a
situation. All of our unit tests are written using built-in 'unittest'
module. We've a requirement where we want to run a method only once
for our unit tests. Some background: all of our tests are sub-classes
of unittest.TestCase module just like following (copy pasting from
idle)

class Calculator(unittest.TestCase):

    def setUp(self): pass
    def tearDown(self): pass


    def test_add(self):

        print 'adder'
        print '---------------'

    def test_multiply(self):
        print 'multiplier'
        print '---------------'

    def test_divide(self):
        print '==========='
        print 'Divide test'
        print '==========='

Our requirement is that for every unit test class we want to run a
method only once. Method setUp() won't help because it will be called
before every test method. I've tried using the following

def __init__(self):
        unittest.TestCase.__init__(self)

but it throws the following error


E:\PyPy\Practice>python runner.py

Traceback (most recent call last):
    suite  = unittest.defaultTestLoader.loadTestsFromNames
(['Tests.Calculator.Te
stCase'])
  File "C:\Python25\lib\unittest.py", line 565, in loadTestsFromNames
    suites = [self.loadTestsFromName(name, module) for name in names]
  File "C:\Python25\lib\unittest.py", line 547, in loadTestsFromName
    return self.loadTestsFromTestCase(obj)
  File "C:\Python25\lib\unittest.py", line 507, in
loadTestsFromTestCase
    return self.suiteClass(map(testCaseClass, testCaseNames))
TypeError: __init__() takes exactly 1 argument (2 given)

So I'm completely stumped as to how to create a method that will only
be called only once for Calculator class. Can you please suggest any
ideas? Any help will be highly appreciated. Thanks in advance.