Python · testing

interaction-only-test

python:interaction-only-test

Tests should verify outcomes, not only mock interaction bookkeeping.

Code: SARJ063
Default: error
Fix: none
Languages: python

Why

Interaction-only assertions pin implementation call sequences without proving useful behavior.

Fix

Assert returned data, persisted state, emitted output, or another observable outcome.

Before / after

Executed by this rule’s unit tests.

Before

Test checks only collaborator calls

tests/test_notify.py · focus

def test_notify():
    notify(mailer, audit, user)
    mailer.send.assert_called_once_with(user.email)
    audit.record.assert_called_once_with("notified")

After

Test checks the returned notification

tests/test_notify.py · focus

def test_notify():
    result = notify(mailer, audit, user)
    mailer.send.assert_called_once_with(user.email)
    audit.record.assert_called_once_with("notified")
    assert result.status == "sent"

Limits

Only collected tests with multiple mock targets and no outcome assertion are reported.