Python · testing

over-mocked-test

python:over-mocked-test

Tests should not replace more than five distinct collaborators.

Code: SARJ062
Default: error
Fix: none
Languages: python

Why

Broad mock wiring couples tests to implementation details while exercising little production behavior.

Fix

Use real dependencies or a higher-level test harness and mock only true external boundaries.

Before / after

Executed by this rule’s unit tests.

Before

Test patches six collaborators

tests/test_service.py · focus

from unittest.mock import patch

@patch("app.mod0.collaborator")
@patch("app.mod1.collaborator")
@patch("app.mod2.collaborator")
@patch("app.mod3.collaborator")
@patch("app.mod4.collaborator")
@patch("app.mod5.collaborator")
def test_run(a, b, c, d, e, f):
    assert run() == 1

After

Test patches one external boundary

tests/test_service.py · focus

from unittest.mock import patch

@patch("app.payment_gateway")
def test_run(gateway):
    assert run() == 1

Limits

Only collected tests are analyzed; configuration knobs do not count as collaborators.