testing - How to mock a class in Python? -

i'm new python, used work ruby.

i'm trying tests python can't figure out how mock class test.

let's have real class:

from database import db class foo:   def do_it(self):     x = {'key': 'value'}     db.save(x)     # other stuff x     return x 

now, want test if i'm doing x returns me right result, , want test if db.save called x parameter, don't want save x database. see if db.save being called, can use mock framework, how can tell foo class need use mock object , not real db object?

thank you.

edit: sorry, example wasn't enough need accomplish.

let's see new example:

from database import db class foo:   db.connect()   def do_it(self):     x = {'key': 'value'}     db.save(x)     # other stuff x     return x 

and instance, let's database down.

when import foo, raises connection error , not have time mock db.

what should do??

the answer is, don't write classes that. it's strange way anyway - there shouldn't executable code @ class level, other attribute , method definitions. should setup connection in __init__ method.

class foo(object):     def __init__(self, *args, **kwargs):         db.connect()