Python : Assert that variable is instance method?

inspect.ismethod is what you want to find out if you definitely have a method, rather than just something you can call.

import inspectdef foo(): passclass Test(object):    def method(self): passprint inspect.ismethod(foo) # Falseprint inspect.ismethod(Test) # Falseprint inspect.ismethod(Test.method) # Trueprint inspect.ismethod(Test().method) # Trueprint callable(foo) # Trueprint callable(Test) # Trueprint callable(Test.method) # Trueprint callable(Test().method) # True

callable is true if the argument if the argument is a method, a function (including lambdas), an instance with __call__ or a class.

Methods have different properties than functions (like im_class and im_self). So you want

assert inspect.ismethod(Test().method)  

If you want to know if it is precisely an instance method use the following function. (It considers methods that are defined on a metaclass and accessed on a class class methods, although they could also be considered instance methods)

import typesdef is_instance_method(obj):    """Checks if an object is a bound method on an instance."""    if not isinstance(obj, types.MethodType):        return False # Not a method    if obj.im_self is None:        return False # Method is not bound    if issubclass(obj.im_class, type) or obj.im_class is types.ClassType:        return False # Method is a classmethod    return True

Usually checking for that is a bad idea. It is more flexible to be able to use any callable() interchangeably with methods.