Avoid converting functions to methods in a class

Daniel Fetchinson fetchinson at googlemail.com
Tue Feb 23 16:39:11 CET 2010


> I have a convention when writing unit tests to put the target of the test
> into a class attribute, as follows:
>
> class MyTest(unittest.TestCase):
>     target = mymodule.someclass
>
>     def test_spam(self):
>         """Test that someclass has a spam attribute."""
>         self.failUnless(hasattr(self.target, 'spam'))
>
>
> It works well until I write a test for stand-alone functions:
>
> class AnotherTest(unittest.TestCase):
>     target = mymodule.function
>
>     def test_foo(self):
>         self.assertEquals(self.target('a', 'b'), 'foo')
>
> The problem is that target is turned into a method of my test class, not
> a standalone function, and I get errors like:
>
> TypeError: function() takes exactly 2 arguments (3 given)
>
> The solution I currently use is to drop the target attribute in this
> class, and just refer to mymodule.function in each individual test. I
> don't like this solution because it violates Once And Only Once: if the
> function changes name, I have to make many edits to the test suite rather
> than just one.

Isn't staticmethod the trick you need?

HTH,
Daniel


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