pytest-django for Django testing - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is pytest-django?

pytest-django is a plugin for pytest that makes it easier to test Django applications by providing Django-specific fixtures and helpers.

beginner

How do you enable database access in a pytest-django test?

You add the pytest marker @pytest.mark.django_db to the test function or use the db fixture to allow database access during the test.

beginner

What is the purpose of the client fixture in pytest-django?

The client fixture provides a Django test client instance that lets you simulate HTTP requests to your Django application in tests.

beginner

How can you run only Django tests using pytest-django?

You can run Django tests by simply running pytest in your project directory. pytest-django automatically discovers Django tests based on your test files and settings.

intermediate

What is the benefit of using pytest fixtures in Django testing?

pytest fixtures help set up and tear down test data or state cleanly and reuse code across tests, making tests easier to write and maintain.

Which pytest-django fixture allows you to simulate HTTP requests?

A client

B db

C settings

D user

The client fixture provides a Django test client to simulate HTTP requests.

How do you mark a test to use the database in pytest-django?

A @pytest.mark.django_db

B @pytest.mark.use_db

C @pytest.mark.database

D @pytest.mark.db_access

The correct marker to enable database access is @pytest.mark.django_db.

What command runs Django tests with pytest-django?

A django-admin test

B python manage.py test

C pytest

D pytest-django run

Running pytest in your project runs Django tests when pytest-django is installed.

Which of these is NOT a benefit of pytest fixtures in Django testing?

A Reusing setup code

B Improved test readability

C Clean test setup and teardown

D Automatic database migrations

pytest fixtures do not handle database migrations automatically; migrations are managed separately.

What does the db fixture in pytest-django do?

A Creates a test client

B Provides database access for tests

C Mocks database calls

D Resets database settings

The db fixture allows tests to access the database.

Explain how pytest-django helps in testing Django applications.

Think about what makes Django testing easier with pytest-django.

Describe the steps to write a simple database test using pytest-django.

Focus on enabling database and writing assertions.

Practice

1. What is the main purpose of using @pytest.mark.django_db in pytest-django tests?

easy

A. To skip the test when the database is not available

B. To disable database migrations during the test

C. To mark the test as a slow test

D. To allow the test to access and modify the Django database

Solution

1. Step 1: Understand the role of @pytest.mark.django_db

   This marker tells pytest that the test needs database access, so pytest sets up the test database properly.

2. Step 2: Identify what happens without the marker

   Without this marker, tests cannot access or modify the database and will fail if they try.

3. Final Answer:

   To allow the test to access and modify the Django database -> Option D

4. Quick Check:

   Database access marker = B [OK]

Hint: Use @pytest.mark.django_db to enable DB access in tests [OK]

Common Mistakes:

• Thinking it skips tests instead of enabling DB access
• Confusing it with marking tests as slow
• Assuming it disables migrations

2. Which of the following is the correct way to use the Django test client fixture in pytest-django?

easy

A. def test_view(client): response = client.get('/'); assert response.status_code == 200

B. def test_view(): response = client.get('/'); assert response.status_code == 200

C. def test_view(client): response = client.post('/'); assert response.status_code = 200

D. def test_view(client): response = client.get('/'); assert response.status == 200

Solution

1. Step 1: Check the function signature and usage

   The test function must accept the client fixture as a parameter to use it.

2. Step 2: Verify the assertion syntax

   The assertion must use == to compare response.status_code to 200.

3. Final Answer:

   def test_view(client): response = client.get('/'); assert response.status_code == 200 -> Option A

4. Quick Check:

   Correct fixture use and assertion = C [OK]

Hint: Pass client as parameter and use response.status_code == 200 [OK]

Common Mistakes:

• Not passing client as a parameter
• Using single = instead of == in assertion
• Checking response.status instead of response.status_code

3. Given the following test code using pytest-django, what will be the output when running the test?

import pytest
from django.contrib.auth.models import User

@pytest.mark.django_db
def test_user_count():
    User.objects.create(username='alice')
    User.objects.create(username='bob')
    count = User.objects.count()
    assert count == 2
    print(count)

medium

A. Test fails because count is 0

B. Test passes and prints 2

C. Test raises a database error

D. Test passes but prints 0

Solution

1. Step 1: Analyze database access and object creation

   The test uses @pytest.mark.django_db, so it can create User objects in the test database.

2. Step 2: Count the User objects and assert

   Two users are created, so User.objects.count() returns 2, matching the assertion.

3. Final Answer:

   Test passes and prints 2 -> Option B

4. Quick Check:

   User count = 2 [OK]

Hint: Mark test with django_db to create and count users correctly [OK]

Common Mistakes:

• Forgetting @pytest.mark.django_db causes DB errors
• Assuming count is zero without creation
• Confusing print output with test result

4. Identify the error in this pytest-django test code and how to fix it:

def test_create_user():
    User.objects.create(username='charlie')
    assert User.objects.count() == 1

medium

A. Test function name should start with 'test_'

B. User model is not imported

C. Missing @pytest.mark.django_db decorator to allow DB access

D. Assertion should check for 0 instead of 1

Solution

1. Step 1: Check database access requirement

   The test tries to create a User in the database but lacks @pytest.mark.django_db, so DB access is not allowed.

2. Step 2: Fix by adding the missing decorator

   Adding @pytest.mark.django_db above the test function enables database access and fixes the error.

3. Final Answer:

   Missing @pytest.mark.django_db decorator to allow DB access -> Option C

4. Quick Check:

   DB access decorator missing = D [OK]

Hint: Add @pytest.mark.django_db to tests using the database [OK]

Common Mistakes:

• Not adding the django_db marker
• Assuming import errors without checking imports
• Misunderstanding assertion values

5. You want to test a Django view that requires a logged-in user using pytest-django. Which is the best way to simulate a logged-in user in your test?

hard

A. Use the client.force_login(user) method after creating a user in the test database

B. Set a session variable manually without creating a user

C. Call the view function directly without using the client fixture

D. Use @pytest.mark.django_db without logging in the user

Solution

1. Step 1: Understand how to simulate login in pytest-django

   The client.force_login(user) method logs in the user for the test client session.

2. Step 2: Create a user in the test database first

   You must create a user in the test database (with @pytest.mark.django_db) before calling force_login.

3. Final Answer:

   Use the client.force_login(user) method after creating a user in the test database -> Option A

4. Quick Check:

   Use force_login with created user = A [OK]

Hint: Create user and call client.force_login(user) to simulate login [OK]

Common Mistakes:

• Trying to set session manually without user
• Calling views directly without client
• Forgetting to create user before login