pytest and Failed: Database access not allowed, use the "django_db" mark, or the "db" or "transactional_db" fixtures to enable it

Question

During invoking pytest from the shell I get the following output, because my test is stored in apps.business.metrics.tools.tests.py, and during import of the module

apps/business/metrics/widgets/employees/utilization.py

makes a live call to SQL during module invocation. This is done by

get_metric_columns('EmployeeUtilization', shapers=SHAPERS)

and pytest complaints:

➜ pytest
=========================================================================== test session starts ===========================================================================
platform linux -- Python 3.6.8, pytest-4.0.0, py-1.7.0, pluggy-0.8.0
Django settings: config.settings.local (from ini file)
rootdir: /home/dmitry/Projects/analytics/backend, inifile: pytest.ini
plugins: django-3.4.7, pylama-7.6.6, django-test-plus-1.1.1, celery-4.2.1
collected 60 items / 1 errors                                                                                                                                             

================================================================================= ERRORS ==================================================================================
__________________________________________________________ ERROR collecting apps/business/metrics/tools.tests.py __________________________________________________________
../../../.pyenv/versions/3.6.8/envs/cam/lib/python3.6/site-packages/py/_path/local.py:668: in pyimport
    __import__(modname)
apps/business/metrics/__init__.py:3: in <module>
    from .widgets import *  # noqa
apps/business/metrics/widgets/__init__.py:1: in <module>
    from . import help  # noqa
apps/business/metrics/widgets/help.py:1: in <module>
    from .employees.utilization import EmployeeSwarmUtilization
apps/business/metrics/widgets/employees/utilization.py:19: in <module>
    get_metric_columns('EmployeeUtilization', shapers=SHAPERS)
apps/business/metrics/tools.py:132: in get_metric_columns
    m = get_metric(metric, period=p, shapers=shapers)
apps/business/metrics/data/__init__.py:23: in get_metric
    return metrics[name](*args, **kwargs)
apps/business/metrics/data/abstract.py:441: in __init__
    self._to_dataframe(self.sql or self._ingest())
apps/business/metrics/data/abstract.py:472: in _to_dataframe
    source, connection, params=query_params, index_col=self.index
../../../.pyenv/versions/3.6.8/envs/cam/lib/python3.6/site-packages/pandas/io/sql.py:381: in read_sql
    chunksize=chunksize)
../../../.pyenv/versions/3.6.8/envs/cam/lib/python3.6/site-packages/pandas/io/sql.py:1413: in read_query
    cursor = self.execute(*args)
../../../.pyenv/versions/3.6.8/envs/cam/lib/python3.6/site-packages/pandas/io/sql.py:1373: in execute
    cur = self.con.cursor()
../../../.pyenv/versions/3.6.8/envs/cam/lib/python3.6/site-packages/django/db/backends/base/base.py:255: in cursor
    return self._cursor()
../../../.pyenv/versions/3.6.8/envs/cam/lib/python3.6/site-packages/django/db/backends/base/base.py:232: in _cursor
    self.ensure_connection()
E   Failed: Database access not allowed, use the "django_db" mark, or the "db" or "transactional_db" fixtures to enable it.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 1 errors during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
========================================================================= 1 error in 2.43 seconds =========================================================================

Is there a way to handle such situation with pytest?

I understand I can convert the get_metric_columns('EmployeeUtilization', shapers=SHAPERS) into a partial func and change the implementation, but is there any other way around?

Answer 1

Solution:

import pytest


@pytest.mark.django_db
class TestExample:
    def test_one():
        ...

Assume that you've created a TestExample class inside your test file and it should be decorated with @pytest.mark.django_db. It should solve your problem.