boB Stepp wrote:
>> The hard part is to remember to test whenever a negative index is
>> calculated.
>
> I am assuming that this is relevant to what just came before, the use
> of this "or None" check. Is this correct?
No, I mean that you always should test your code against the corner cases.
For example a trivial and seemingly harmless function
def tail(items, size):
return items[-size:]
should return an empty list with size=0 (you might get away with undefined
behaviour for size<0). If you only have a test
class T(unittest.TestCase):
def test_tail(self):
self.assertEqual(tail("abcde", 2), "de")
your coverage tool might be happy, but you are still in for trouble. You
need at least
self.assertEqual(tail("abcde", 0), "")
to be prepared for the 0 == -0 problem.
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