Avoid converting functions to methods in a class
jeanmichel at sequans.com
Tue Feb 23 13:50:15 CET 2010
Steven D'Aprano wrote:
> 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.
> Are there any better solutions?
It looks like it works when declaring foo as static:
target = staticmethod(foo)
self.assertEquals(self.target('a', 'b'), 'foo')
...AssertionError: 'fooo' != 'foo'
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