Pytest fixture for a class through self not as method argument

Often I’ll write a test class that uses a pytest fixture in every method. Here’s an example. I’d like to be able to avoid having to write the fixture name in the signature of every method. It’s not DRY. How can this be done?

I would like to be able to access the fixture by giving the fixture as an attribute of the test class. In this example, I would like to see the google fixture as an attribute of TestGoogle. Is this possible?

from bs4 import BeautifulSoup
import pytest
import requests

@pytest.fixture()
def google():
    return requests.get("https://www.google.com")


class TestGoogle:
    def test_alive(self, google):
        assert google.status_code == 200

    def test_html_title(self, google):
        soup = BeautifulSoup(google.content, "html.parser")
        assert soup.title.text.upper() == "GOOGLE"

Answers:

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Method 1

Sure, just use an autouse fixture. Here is the relevant spot in pytest docs. In your example, the change would be introducing an extra fixture (I named it _request_google_page):

from bs4 import BeautifulSoup
import pytest
import requests

@pytest.fixture()
def google():
    return requests.get("https://www.google.com")


class TestGoogle:

    @pytest.fixture(autouse=True)
    def _request_google_page(self, google):
        self._response = google

    def test_alive(self):
        assert self._response.status_code == 200

    def test_html_title(self):
        soup = BeautifulSoup(self._response.content, "html.parser")
        assert soup.title.text.upper() == "GOOGLE"

You could even drop the google fixture completely and move the code to _request_google_page:

@pytest.fixture(autouse=True)
def _request_google_page(self):
    self._response = requests.get("https://www.google.com")

Note that _request_google_page will be called once per test by default, so each test will get a new response. If you want the response to be initialized once and reused throughout all tests in the TestGoogle class, adjust the fixture scopes (scope='class' for _request_google_page and scope='module' or scope='session' for google). Example:

from bs4 import BeautifulSoup
import pytest
import requests


@pytest.fixture(scope='module')
def google():
    return requests.get("https://www.google.com")


@pytest.fixture(autouse=True, scope='class')
def _request_google_page(request, google):
    request.cls._response = google


class TestGoogle:

    def test_alive(self):
        assert self._response.status_code == 200

    def test_html_title(self):
        soup = BeautifulSoup(self._response.content, "html.parser")
        assert soup.title.text.upper() == "GOOGLE"

Method 2

I had to solve a similar problem and the accepted solution didn’t work for me with a class-scoped fixture.

I wanted to call a fixture once per test class and re-use the value in test methods using self. This is actually what the OP was intending to do as well.

You can use the request fixture to access the class that’s using it (request.cls) and assign the fixture value in a class attribute. Then you can access this attribute from self. Here’s the full snippet:

from bs4 import BeautifulSoup
import pytest
import requests

@pytest.fixture(scope="class")
def google(request):
    request.cls.google = requests.get("https://www.google.com")


@pytest.mark.usefixtures("google")
class TestGoogle:
    def test_alive(self):
        assert self.google.status_code == 200

    def test_html_title(self):
        soup = BeautifulSoup(self.google.content, "html.parser")
        assert soup.title.text.upper() == "GOOGLE"

Hope that helps anyone else coming to this question.

Method 3

import pytest
from sqlalchemy import create_engine

@pytest.fixture(scope="class")
def test_connection():
    engine = "abc"#create_engine()
    return engine

@pytest.fixture(scope="class")
def test_patient_id():
    engine = "123"#create_engine()
    return engine


@pytest.mark.usefixtures("test_connection","test_patient_id")
class TestRuleEngine:
    def test_table_setup(self, test_connection, test_patient_id):
        assert 1
        assert test_connection=="abc"
        assert test_patient_id=="123"
    def test_data_insert(self):
        assert 1
    def test_data_delete(self):
        assert 1
    def test_table_delete(self):
        assert 1

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0