Test Models with Pytest¶

In this guide we are going to:

Setup our project for testing with pytest.
Create tests for the CustomUser model.
Create tests for the Post model.
Create tests for the Comment model.
Create tests for the Tag model.
Execute the test suite.

Pre-requisites¶

Requires the Create Django Models for the Blog API guide to be completed.

Guide code:¶

test-models-with-pytest branch in the GitHub repository.

Setup for Testing with Pytest¶

Create folder for tests /src/tests/ and add an empty /src/tests/__init__.py file to it:

mkdir src/tests
touch src/tests/__init__.py

Create file /src/tests/pytest.ini to configure pytest:

[pytest]
DJANGO_SETTINGS_MODULE = blogapi.settings

testpaths =
    src/tests

pythonpath =
    src

addopts = -v

markers =
    model: mark test as model-related

Configure VSCode for `pytest`¶

Open the command palete (Ctrl-Shift-P)
Select Python: Configure Tests command.
Select pytest as testing framework.
Select src as folder to search for tests.

Test the `CustomUser` Model¶

Let’s create Python pacakge for accounts app tests:

mkdir src/tests/accounts
touch src/tests/accounts/__init__.py

And now let’s create a test class to test the CustomUser model with first test.

# /src/tests/accounts/test_models.py
from accounts.models import CustomUser

class TestCustomUser:
    def test_should_be_returned_by_get_user_model(self):
        user_model = get_user_model()
        assert user_model is CustomUser

Execute the tests¶

Execute the tests from the command line:

pytest

================================== test session starts ===================================
platform linux -- Python 3.10.13, pytest-8.3.2, pluggy-1.5.0
django: version: 5.0.7, settings: blogapi.settings (from ini)
rootdir: /workspaces/django-for-apis-cookbook-with-blog
configfile: pytest.ini
testpaths: src/tests
plugins: anyio-4.4.0, cov-5.0.0, django-4.8.0
collected 1 item

src/tests/accounts/test_models.py::TestCustomUser::test_should_be_recognized_as_user_model_by_django_auth PASSED [100%]

=================================== 1 passed in 0.04s ====================================

Exclude model tests¶

In pytest.ini we defined model mark which allows us to selectively include or exclude model tests.

pytest -m "not model"

=============================================== test session starts ================================================
platform linux -- Python 3.10.13, pytest-8.3.2, pluggy-1.5.0
django: version: 5.0.7, settings: blogapi.settings (from ini)
rootdir: /workspaces/django-for-apis-cookbook-with-blog
configfile: pytest.ini
testpaths: src/tests
plugins: anyio-4.4.0, cov-5.0.0, django-4.8.0
collected 1 item / 1 deselected / 0 selected

============================================== 1 deselected in 0.06s ===============================================

More `CustomUser` tests¶

We are going to create tests that user can be created and deleted.

First let’s create a user fixture which could be used in all project tests:

# src/conftest.py
import pytest

from accounts.models import CustomUser

@pytest.fixture(name="user")
def given_user():
    u = CustomUser.objects.create()
    return u

And add create delete tests to src/tests/accounts/test_models.py:

# ............
class TestCustomUser:
    # ............

    @pytest.mark.django_db
    def test_should_create_user_instance(self):
        # WHEN New user model instance is created
        u = CustomUser.objects.create()
        # THEN the object is a CustomUser instance
        assert isinstance(u, CustomUser)
        # AND is persisted in the database
        u.refresh_from_db()

    @pytest.mark.django_db
    def test_should_delete_user_instance(self, user: CustomUser):
        # WHEN User is deleted
        user.delete()
        # THEN the user instance is no longer found in the database
        with pytest.raises(CustomUser.DoesNotExist):
            user.refresh_from_db()

Running the tests:

================================================ test session starts ================================================
platform linux -- Python 3.10.13, pytest-8.3.2, pluggy-1.5.0 -- /home/codespace/.python/current/bin/python
cachedir: .pytest_cache
django: version: 5.0.7, settings: blogapi.settings (from ini)
rootdir: /workspaces/django-for-apis-cookbook-with-blog
configfile: pytest.ini
testpaths: src/tests
plugins: anyio-4.4.0, cov-5.0.0, django-4.8.0
collected 3 items

src/tests/accounts/test_models.py::TestCustomUser::test_should_create_user_instance PASSED                    [ 33%]
src/tests/accounts/test_models.py::TestCustomUser::test_should_delete_user_instance PASSED                    [ 66%]
src/tests/accounts/test_models.py::TestCustomUser::test_should_be_recognized_as_user_model_by_django_auth PASSED [100%]

================================================= 3 passed in 0.23s =================================================

Test the `Post` Model¶

Create test package for posts app:

mkdir src/tests/posts
touch src/tests/posts/__init__.py

And add a src/tests/posts/test_models.py file to it:

import pytest

from posts.models import Post

pytestmark = pytest.mark.model

class TestPost:

    @pytest.mark.django_db
    def test_should_create_post_instance(self, user):
        # WHEN New post model instance is created
        p = Post.objects.create(author=user)
        # THEN the object is a Post instance
        assert isinstance(p, Post)
        # AND is persisted in the database
        p.refresh_from_db()

    @pytest.mark.django_db
    def test_should_delete_post_instance(self, post: Post):
        # WHEN Post is deleted
        post.delete()
        # THEN the post instance is no longer found in the database
        with pytest.raises(Post.DoesNotExist):
            post.refresh_from_db()

For above test we also created a post fixture in src/tests/conftest.py:

# src/tests/conftest.py
import pytest

from accounts.models import CustomUser
from posts.models import Post

# .......................

@pytest.fixture(name="post")
def given_post(user):
    p = Post.objects.create(
        author=user,
    )
    return p

Test the `Comment` Model¶

Add the tests for the Comment model to src/tests/posts/test_models.py:

# src/tests/posts/test_models.py
import pytest

from posts.models import Comment, Post

pytestmark = pytest.mark.model

# .........................

class TestComment:
    @pytest.mark.django_db
    def test_should_create_comment_instance(self, post, user):
        # WHEN New comment model instance is created
        c = Comment.objects.create(post=post, author=user)
        # THEN the object is a Comment instance
        assert isinstance(c, Comment)
        # AND is persisted in the database
        c.refresh_from_db()
        # AND comment is attached to post
        assert c in post.comments.all()

    @pytest.mark.django_db
    def test_should_delete_comment_instance(self, comment: Comment):
        # WHEN Post is deleted
        comment.delete()
        # THEN the post instance is no longer found in the database
        with pytest.raises(Comment.DoesNotExist):
            comment.refresh_from_db()

    @pytest.mark.django_db
    def test_should_delete_comment_when_post_is_deleted(self, post: Post, comment: Comment):
        # WHEN post is deleted
        post.delete()
        # THEN the comment is also deleted
        with pytest.raises(Comment.DoesNotExist):
            comment.refresh_from_db()

Also add a comment fixture to src/tests/conftest.py:

import pytest

from accounts.models import CustomUser
from posts.models import Comment, Post

# .....................

@pytest.fixture(name="comment")
def given_comment(post, user):
    c = Comment.objects.create(
        post=post,
        author=user,
    )
    return c

Test the `Tag` Model¶

Add the tests for the Tag model to src/tests/posts/test_models.py:

# src/tests/posts/test_models.py
import pytest

from posts.models import Comment, Post, PostTag, Tag

pytestmark = pytest.mark.model

# ........................

class TestTag:
    @pytest.mark.django_db
    def test_should_create_tag_instance(self):
        # WHEN New tag model instance is created
        t = Tag.objects.create(name="tag")
        # THEN the object is a Comment instance
        assert isinstance(t, Tag)
        # AND is persisted in the database
        t.refresh_from_db()

    @pytest.mark.django_db
    def test_should_delete_tag_instance(self, tag: Tag):
        # WHEN Tag is deleted
        tag.delete()
        # THEN the tag instance is no longer found in the database
        with pytest.raises(Tag.DoesNotExist):
            tag.refresh_from_db()

    @pytest.mark.django_db
    def test_should_remove_tag_from_post_when_tag_is_deleted(
        self, post_with_tag: Post, tag: Tag
    ):
        # WHEN tag is deleted
        tag.delete()
        # THEN tag is no longer assigned to post
        assert 0 == len(post_with_tag.tags.all())

    @pytest.mark.django_db
    def test_should_not_delete_tag_when_post_is_deleted(self, post_with_tag: Post, tag: Tag):
        # WHEN post is deleted
        post_with_tag.delete()
        # THEN the tag is still in the database
        tag.refresh_from_db()
        # AND post link to tag is deleted
        assert not PostTag.objects.filter(tag=tag).all()

Add also fixtures to src/tests/conftest.py:

# src/tests/conftest.py
import pytest

from accounts.models import CustomUser
from posts.models import Comment, Post, Tag

# ...................................

@pytest.fixture(name="post_with_tag")
def given_post_with_tag(post, tag):
    post.tags.set([tag])
    return post

@pytest.fixture(name="tag")
def given_tag(post, user):
    t = Tag.objects.create(
        name="Tag",
    )
    return t

Execute the test suite¶

Running pytest from the command line passes all tests:

================================================ test session starts ================================================
platform linux -- Python 3.10.13, pytest-8.3.2, pluggy-1.5.0 -- /home/codespace/.python/current/bin/python
cachedir: .pytest_cache
django: version: 5.0.7, settings: blogapi.settings (from ini)
rootdir: /workspaces/django-for-apis-cookbook-with-blog
configfile: pytest.ini
testpaths: src/tests
plugins: anyio-4.4.0, cov-5.0.0, django-4.8.0
collected 12 items

src/tests/accounts/test_models.py::TestCustomUser::test_should_create_user_instance PASSED                    [  8%]
src/tests/accounts/test_models.py::TestCustomUser::test_should_delete_user_instance PASSED                    [ 16%]
src/tests/posts/test_models.py::TestPost::test_should_create_post_instance PASSED                             [ 25%]
src/tests/posts/test_models.py::TestPost::test_should_delete_post_instance PASSED                             [ 33%]
src/tests/posts/test_models.py::TestComment::test_should_create_comment_instance PASSED                       [ 41%]
src/tests/posts/test_models.py::TestComment::test_should_delete_comment_instance PASSED                       [ 50%]
src/tests/posts/test_models.py::TestComment::test_should_delete_comment_when_post_is_deleted PASSED           [ 58%]
src/tests/posts/test_models.py::TestTag::test_should_create_tag_instance PASSED                               [ 66%]
src/tests/posts/test_models.py::TestTag::test_should_delete_tag_instance PASSED                               [ 75%]
src/tests/posts/test_models.py::TestTag::test_should_remove_tag_from_post_when_tag_is_deleted PASSED          [ 83%]
src/tests/posts/test_models.py::TestTag::test_should_not_delete_tag_when_post_is_deleted PASSED               [ 91%]
src/tests/accounts/test_models.py::TestCustomUser::test_should_be_recognized_as_user_model_by_django_auth PASSED [100%]

================================================ 12 passed in 0.38s =================================================

Test Models with Pytest¶

Pre-requisites¶

Guide code:¶

Setup for Testing with Pytest¶

Configure VSCode for `pytest`¶

Test the `CustomUser` Model¶

Execute the tests¶

Exclude model tests¶

More `CustomUser` tests¶

Test the `Post` Model¶

Test the `Comment` Model¶

Test the `Tag` Model¶

Execute the test suite¶

Django for APIs Cookbook

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Related Topics

Test Models with Pytest¶

Pre-requisites¶

Guide code:¶

Setup for Testing with Pytest¶

Configure VSCode for pytest¶

Test the CustomUser Model¶

Execute the tests¶

Exclude model tests¶

More CustomUser tests¶

Test the Post Model¶

Test the Comment Model¶

Test the Tag Model¶

Execute the test suite¶

Configure VSCode for `pytest`¶

Test the `CustomUser` Model¶

More `CustomUser` tests¶

Test the `Post` Model¶

Test the `Comment` Model¶

Test the `Tag` Model¶