python unittest: can't call decorated test

Question

I have a pretty large test suite and I decorated some of the test_* functions. Now I can't call them by ./test.py MySqlTestCase.test_foo_double, python3.2 complains that: ValueError: no such test method in <class '__main__.MySqlTestCase'>: result. My decorator code looks like this:

def procedure_test(procedure_name, arguments_count, returns):

    '''Decorator for procedure tests, that simplifies testing whether procedure
    with given name is available, whether it has given number of arguments
    and returns given value.'''

    def decorator(test):
        def result(self):
            procedure = self.db.procedures[self.case(procedure_name)]
            self.assertEqual(len(procedure.arguments), arguments_count)
            self.assertEqual(procedure.returns, 
                             None if returns is None else self.case(returns))
            test(self, procedure)
        return result
    return decorator

and the test method:

@procedure_test('foo_double', 0, 'integer')
def test_foo_double(self, procedure):
    self.assertEqual(procedure.database, self.db)
    self.assertEqual(procedure.sql, 'RETURN 2 * value')
    self.assertArguments(procedure, [('value', 'int4')])

score 7 · Accepted Answer · answered Nov 17 '11 at 11:42

7

I think the problem is that the decorated function doesn't have the same name and, also, it doesn't satisfy the pattern to be considered a test method.

Using functools.wrap to decorate decorator should fix your problem. More information here.

answered Nov 17 '11 at 11:42

jcollado

39,419
8
102
133

score 2 · Answer 2 · answered Apr 02 '20 at 18:47

This is a simple way of solving this issue.

from functools import wraps

def your_decorator(func):
    @wraps(func)
    def wrapper(self):
        #Do Whatever
        return func(self)
    return wrapper

class YourTest(APITestCase):
    @your_decorator
    def example(self):
        #Do your thing

score 1 · Answer 3 · answered Dec 19 '12 at 15:54

1

This help me:

from functools import wraps

...

@wraps(procedure_name)
def decorator(test):

answered Dec 19 '12 at 15:54

Dmitry Dubovitsky

2,186
1
16
24

score 1 · Answer 4 · edited May 23 '17 at 12:32

1

Based on this post:

You can do it this way:

def decorator(test):
    def wrapper(self):
        # do something interesting
        test(self)
        # do something interesting
    wrapper.__name__ = test.__name__
    return wrapper

This solution has two advantages over method with @functools.wrap:

doesn't need anything to import
doesn't need to know test name when decorator is created

Thanks to the second feature of this solution, it is possible to create decorators for many tests.

edited May 23 '17 at 12:32

Community

1
1

answered Sep 02 '16 at 11:27

pt12lol

2,332
1
22
48

1

This is the head-shot that kill the issue by 1 single blow. Must be the accepted one to me. – Nam G VU Jul 31 '18 at 09:51
Note that functools.wraps does more than just setting name, such as docstring preservation. And the normal use of `wraps` in a decorator is ``` def decorator(func): @wraps(func) wrapper(*args) ... ```` Which can similarly wrap arbitrarily-named test cases. – isturdy Dec 18 '18 at 23:02

python unittest: can't call decorated test

4 Answers4

Linked