Giving parameters into TestCase from Suite in python

Question

From python documentation(http://docs.python.org/library/unittest.html):

import unittest

class WidgetTestCase(unittest.TestCase):
    def setUp(self):
        self.widget = Widget('The widget')

    def tearDown(self):
        self.widget.dispose()
        self.widget = None

    def test_default_size(self):
        self.assertEqual(self.widget.size(), (50,50),
                         'incorrect default size')

    def test_resize(self):
        self.widget.resize(100,150)
        self.assertEqual(self.widget.size(), (100,150),
                         'wrong size after resize')

Here is, how invoke those testcase:

def suite():
    suite = unittest.TestSuite()
    suite.addTest(WidgetTestCase('test_default_size'))
    suite.addTest(WidgetTestCase('test_resize'))
    return suite

Is it possible to insert parameter custom_parameter into WidgetTestCase like:

class WidgetTestCase(unittest.TestCase):
    def setUp(self,custom_parameter):
        self.widget = Widget('The widget')
        self.custom_parameter=custom_parameter

?

Answer 1

What I've done is in test_suite module just added

WidgetTestCase.CustomParameter="some_address"

The simplest solutions are the best :)

Answer 2

I've found a way to do this, but it's a bit of a cludge.

Basically, what I do is add, to the TestCase, an __init__ method which defines a 'default' parameter and a __str__ so that we can distinguish cases:

class WidgetTestCase(unittest.TestCase):

    def __init__(self, methodName='runTest'):
        self.parameter = default_parameter
        unittest.TestCase.__init__(self, methodName)

    def __str__(self):
        ''' Override this so that we know which instance it is '''
        return "%s(%s) (%s)" % (self._testMethodName, self.currentTest, unittest._strclass(self.__class__))

Then in suite(), I iterate over my test parameters, replacing the default parameter with one specific to each test:

def suite():
    suite = unittest.TestSuite()

    for test_parameter in test_parameters:
        loadedtests = unittest.TestLoader().loadTestsFromTestCase(WidgetTestCase)
        for t in loadedtests:
            t.parameter = test_parameter
        suite.addTests(loadedtests)

    suite.addTests(unittest.TestLoader().loadTestsFromTestCase(OtherWidgetTestCases))
    return suite

where OtherWidgetTestCases are tests which don't need to be parameterised.

For instance I have a bunch of tests on real data for which a suite of tests need to be applied to each, but I also have some synthetic data sets, designed to test certain edge cases not normally present in the data, and I only need to apply certain tests to those, so they get their own tests in OtherWidgetTestCases.