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Pytest plugin for automatical mocks creation

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  • 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
  • Black and white lists for attributes
  • 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 3.7+


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,
             allowed_methods: Optional[Sequence[str]] = None,
             forbidden_methods: Optional[Sequence[str]] = 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)
  • allowed_methods: sequence of allowed to mock attributes
  • forbidden_methods: sequnce of forbidden to mock attributes
  • 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,
             allowed_methods: Optional[Sequence[str]] = None,
             forbidden_methods: Optional[Sequence[str]] = None)
  • factory: object/function to wrap
  • memory: dicrionary to get/put mocks
  • locked: mode selector
  • allowed_methods: sequence of allowed to mock attributes
  • forbidden_methods: sequnce of forbidden to mock attributes


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

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