Skip to main content

Pytest plugin for automatical mocks creation

Project description


Travis status for master branch Codecov coverage for master branch Pypi version Pypi downloads count


  • No generic automock solution


  • Pytest plugin
  • Autogenerate/autouse mocks for functions and objects
  • Sync and async support
  • Locked mode to be sure mocked objects stay untouched
  • Customizable serialization


  • No support for dunder methods (can be partly solved in future)
  • No support for sync/async generators/contexts
  • Races will break tests, since order counts


pytest-automock is offered under MIT license.


  • python 3.6+


Lets say you have some module

import time

class Network:
    def get_data_from_network(self, x, y):
        return x + y

    def send_data_to_network(self, value):

def logic(x):
    n = Network()
    a, b = 0, 1
    while b < x:
        c = n.get_data_from_network(a, b)
        a, b = b, c
    return b

And you want to create mocks for your Network class (since testing time and sane counts), but you are too lazy to write them...

import pytest
import mymod

def _mocks(automock):
    with automock((mymod, "Network")):

from mymod import logic

def test_logic():
    assert logic(7) == 8
    assert logic(10) == 13

If you run pytest on this setup, then you will see fail:

$ pytest -x
E           RuntimeError: Mock is locked, but '__init__' wanted

automock can work in two modes: locked and unlocked. Locked mode is default, real methods calls of mocked objects are not allowed in this mode. So, above error says that we can't call __init__ of our Network. In locked mode there is no mock-files update also.

To allow real calls and mocks generation automock provides extra cli argument to pytest: --automock-unlocked

$ pytest -x --automock-unlocked
... .
1 passed in 22.09s

After that you can see that tests/mocks/test_logic/mymod/Network file was created. This is mock for your test sequence. Now you can rerun tests and see what happens (you can omit --automock-unlocked key for ensurance, that real object will not be touched (actually even created)).

$ pytest -x
... .
1 passed in 0.04s


automock (fixture)

automock fixture is a context manager

def automock(*pairs,
             storage: Union[str, Path] = "tests/mocks",
             override_name: Optional[str] = None,
             unlocked: Optional[bool] = None,
             encode: Callable[[Any], bytes] = pickle.dumps,
             decode: Callable[[bytes], Any] = pickle.loads)
  • *pairs: pair/tuple of object/module and attribute name (str)
  • storage: root path for storing mocks
  • override_name: forced mock-file name
  • unlocked: mode selector (if omited, selected by --automock-unlocked)
  • encode: encode routine
  • decode: decode routine

automock_unlocked (fixture)

Fixture with default mode from cli parameter (bool).

automock (function)

automock function is not supposed to be used by anyone but automock fixture

def automock(factory: Callable, *,
             memory: Dict,
             locked: bool = True,
             encode: Callable[[Any], bytes] = pickle.dumps,
             decode: Callable[[bytes], Any] = pickle.loads):
  • factory: object/function to wrap
  • memory: dicrionary to get/put mocks
  • locked: mode selector
  • encode: encode routine
  • decode: decode routine


Run tests

Since coverage issue/feature, plugins coverage is broken by default. Workaround:

COV_CORE_SOURCE=pytest_automock COV_CORE_CONFIG=.coveragerc COV_CORE_DATAFILE=.coverage.eager pytest

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Files for pytest-automock, version 0.4.0
Filename, size File type Python version Upload date Hashes
Filename, size pytest_automock-0.4.0-py3-none-any.whl (5.7 kB) File type Wheel Python version py3 Upload date Hashes View hashes
Filename, size pytest-automock-0.4.0.tar.gz (11.3 kB) File type Source Python version None Upload date Hashes View hashes

Supported by

Elastic Elastic Search Pingdom Pingdom Monitoring Google Google BigQuery Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN SignalFx SignalFx Supporter DigiCert DigiCert EV certificate StatusPage StatusPage Status page