Stephen Thorne <[email protected]> added the comment:
I have done some experimentation here and thought through this feature request.
The concept we are trying to deliver is: "I would like to share functionality
between test classes, by having an abstract parent, with concrete leaves"
The metaclass abc.ABCMeta provides functionality that means two things:
- any class with this metaclass (so the class and all its subclasses,
typically) that have @abc.abstractmethod or @abc.abstractproperty decorated
methods will be treated as abstract
- any class that is treated as abstract will raise an exception immediately,
to make it clear to the programmer (and unit tests) that a programming error
has occured.
Following this through, we end up with two ways in which this can go wrong in
unit testing if we ask our unit testing framework to not test abstract classes.
This is a complete example, with both failure modes illustrated:
Consider:
class AbstractTestCase(unittest.TestCase, metaclass=abc.ABCMeta):
...
class FooTest(AbstractTestCase):
def foo(self):
return 1
In this case, AbstractTestCase will not be skipped: this is because without any
abstract methods inside it: it's not actually considered 'abstract', and is a
concrete class.
In the second case:
class AbstractTestCase(unittest.TestCase, metaclass=abc.ABCMeta):
@abc.abstractmethod
def foo(self):
...
@abc.abstractmethod
def bar(self):
...
class FooTest(AbstractTestCase):
def foo(self):
return 1
In this case, because AbstractTestCase has 2 abstract methods, it will be
skipped. No tests run. But also FooTest will be skipped because it has 1
abstract method, and is therefore also abstract.
If this were a 'normal' program, we would see an exception raised when FooTest
is instanciated, but because we're skipping tests in abstract classes, we skip
all the tests and exit with success.
My gut feeling on this is that what we really want is a decorator that says:
Skip this class, and only this class, explicitly. All subclasses are concrete,
only this one is abstract.
----------
nosy: +sthorne
_______________________________________
Python tracker <[email protected]>
<https://bugs.python.org/issue17519>
_______________________________________
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
