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Platform for test doubles in Python (mocks, stubs, and dummies)

Project Description

Welcome to ludibrio



Ludibrio is registered with PyPi. If you have pip, setuptools or Distribute you can install mock with:

$ sudo easy_install ludibrio


The latest official version is 3.0.2. Here’s how to get it:


See the for the current documentation.

Getting involved !

Ludibrio’s development may be viewed and followed on github:

Retrieve the source code using ‘git’:

$ git clone git://

Install package in ‘development mode’ and run tests with doctestcommand:

$ sudo easy_install doctestcommand
$ git clone git://
$ cd ludibrio
$ sudo python develop
$ cd ludibrio
$ doctest

In a nutshell

Test doubles are fake objects that simulate the behavior of a real object for testing purposes.


Mocks are objects pre-programmed with expectations which form a specification of the calls they are expected to receive:

>>> from ludibrio import Mock
>>> with Mock() as MySQLdb:
...     con = MySQLdb.connect('server', 'user', 'XXXX')
...     con.select_db('DB') >> None
...     cursor = con.cursor()
...     cursor.execute('select * from numbers') >> None
...     cursor.fetchall() >> [1,2,3,4,5]
>>> con = MySQLdb.connect('server', 'user', 'XXXX')
>>> con.select_db('DB')
>>> cursor = con.cursor()
>>> cursor.execute('select * from numbers')
>>> cursor.fetchall()
[1, 2, 3, 4, 5]

>>> MySQLdb.validate() #passed


Stubs provide pre-defined answers to method calls made during a test:

>>> from ludibrio import Stub
>>> with Stub() as x:
...     x.anything() >> 'response'
>>> x.anything()

Trivial mocking or stubing for any external module

Ludibrio also offers a replace mode, which basically means if a “from … import …” statement is defined into a ‘with’ scope, the replay mechanism will return a mock object to replace the original object in namespace of the whole Python interpreter (including any modules, etc). There’s a simple example below to illustrate how use it:

>>> from ludibrio import Stub

>>> with Stub() as time:
...     from time import time
...     time() >> 171
>>> from time import time
>>> time()


Two Ludibrio’s powerful features that aren’t found in other mocking systems is the ability of proxying existing objects, or patching a real instance or class.

When an object is proxied, Ludibrio create a Test Double object holding a reference to the real object, allowing expressions passthrough to it(mocked or not, and by default or on request):

>>> from os.path import splitext
>>> with Stub(proxy=splitext) as splitext:
...     splitext('ludibrio/') >> ('/temp/temp','.temp')
>>> splitext('')
('mock', '.py')
>>> splitext('ludibrio/')
('/temp/temp', '.temp')

Release History

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