Avoiding test interdependence in PyTest - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is test interdependence in pytest?

Test interdependence happens when one test depends on another test's result or state. This can cause tests to fail unpredictably.

beginner

Why should tests be independent in pytest?

Independent tests ensure that each test can run alone or in any order without affecting others. This makes debugging easier and test results reliable.

intermediate

How can pytest fixtures help avoid test interdependence?

Fixtures provide fresh setup and teardown for tests. They prepare a clean environment for each test, preventing shared state that causes interdependence.

intermediate

What is a good practice to avoid shared state between tests?

Use fixtures with scope='function' to create isolated environments. Avoid using global variables or shared data that tests can modify.

beginner

Give an example of a pytest fixture that helps avoid test interdependence.

import pytest

@pytest.fixture
def clean_list():
    return []  # fresh list for each test

def test_append(clean_list):
    clean_list.append(1)
    assert clean_list == [1]

def test_empty(clean_list):
    assert clean_list == []

What happens if tests depend on each other in pytest?

A Tests run faster

B Tests always pass

C Tests become easier to write

D Tests may fail unpredictably if run in different order

When tests depend on each other, changing the order or running tests alone can cause failures.

Which pytest feature helps create isolated test environments?

A Fixtures

B Global variables

C Test classes

D Print statements

Fixtures set up fresh data or state for each test, avoiding shared state.

What fixture scope is best to avoid test interdependence?

A module

B function

C session

D package

Function scope runs the fixture fresh for each test, ensuring isolation.

Which practice can cause test interdependence?

A Writing small tests

B Using fixtures for setup

C Using global variables shared by tests

D Running tests in random order

Global variables shared by tests can cause one test to affect another.

How can you check if tests are independent?

A Run tests in random order multiple times

B Run tests only once

C Write tests in one file

D Use print statements

Running tests in random order helps detect interdependence issues.

Explain why avoiding test interdependence is important in pytest.

Think about what happens if one test changes something another test needs.

Describe how pytest fixtures help prevent test interdependence.

Consider how fixtures prepare data or state before tests run.