Unittest - testing properties (read-only attributes)

[Diez B. Roggisch]

Paul Moore wrote:

> I have a class with a read-only attribute, and I want to add a unit
> test to ensure that it really *is* read-only. I can do this as
> 
>     def test_readonly(self):
> """Value and multiplier must be readonly"""
> try:
> self.combat.value = 1
> self.fail("Value is not read only")
> except AttributeError:
> pass
> 
> That works, but it seems a bit clumsy. Is there a better way?


By using setattr, you could refactor the above code into a function. Looks
like this (untested):

def test_readonly(self, instance, attribute, value=1):
 """Value and multiplier must be readonly"""
 try:
    setattr(instance, attribute, value)
    self.fail("Value is not read only")
 except AttributeError:
    pass


Then the testing becomes one line:

self.test_readonly(self.combat, "value")


-- 
Regards,

Diez B. Roggisch