How do I pass parameters to a fixture function which already takes monkeypatch?

[matteobrv]

Hi. I've got the following piece of code which successfully mock the current date so that test_date prints 1999-12-31.

import pytest
import datetime

FAKE_DATE = datetime.datetime(1999, 12, 31)

@pytest.fixture
def patch_datetime(monkeypatch, fake_date=FAKE_DATE):
    # subclass date and override today
    class MyDate(datetime.date):
        @classmethod
        def today(cls):
            return fake_date.date()
    # replace datetime.date with MyDate
    monkeypatch.setattr(datetime, "date", MyDate)

def test_date(patch_datetime):
    print(datetime.date.today())

However, my actual goal is to parametrize test_date so that I can keep one fixture, patch_datetime, and work with multiple mock dates. I tried several approaches to implement this, with no success; the latest attempt looked as follows and tried to use Indirect parametrization:

FAKE_DATES = [
    datetime.datetime(1999, 12, 31),
    datetime.datetime(2000, 12, 31)
]

@pytest.mark.parametrize("patch_datetime", FAKE_DATES, indirect=True)
def test_date(patch_datetime) -> None:
    print(datetime.date.today())

If anyone could point me in the right direction, I'd really appreciate it.

This is the output I get when I run pytest test.py -s:

$ pytest tests.py -s
======================================================================================================== test session starts ========================================================================================================
platform linux -- Python 3.13.1, pytest-8.3.3, pluggy-1.5.0
rootdir: /workspaces/project01
configfile: pyproject.toml
collected 2 items                                                                                                                                                                                                                   

tests_2.py EE

============================================================================================================== ERRORS ===============================================================================================================
___________________________________________________________________________________________ ERROR at setup of test_date[patch_datetime0] ____________________________________________________________________________________________
file /workspaces/project01/05_next_date/tests.py, line 22
  @pytest.mark.parametrize("patch_datetime", FAKE_DATES, indirect=True)
  def test_date(patch_datetime):
file /workspaces/project01/05_next_date/tests.py, line 11
  @pytest.fixture
  def patch_datetime(monkeypatch, fake_date):
E       fixture 'fake_date' not found
>       available fixtures: cache, capfd, capfdbinary, caplog, capsys, capsysbinary, doctest_namespace, monkeypatch, patch_datetime, pytestconfig, record_property, record_testsuite_property, record_xml_attribute, recwarn, tmp_path, tmp_path_factory, tmpdir, tmpdir_factory
>       use 'pytest --fixtures [testpath]' for help on them.

/workspaces/project01/05_next_date/tests.py:11
___________________________________________________________________________________________ ERROR at setup of test_date[patch_datetime1] ____________________________________________________________________________________________
file /workspaces/project01/05_next_date/tests.py, line 22
  @pytest.mark.parametrize("patch_datetime", FAKE_DATES, indirect=True)
  def test_date(patch_datetime):
file /workspaces/python_morsels/05_next_date/tests_2.py, line 11
  @pytest.fixture
  def patch_datetime(monkeypatch, fake_date):
E       fixture 'fake_date' not found
>       available fixtures: cache, capfd, capfdbinary, caplog, capsys, capsysbinary, doctest_namespace, monkeypatch, patch_datetime, pytestconfig, record_property, record_testsuite_property, record_xml_attribute, recwarn, tmp_path, tmp_path_factory, tmpdir, tmpdir_factory
>       use 'pytest --fixtures [testpath]' for help on them.

/workspaces/project01/05_next_date/tests.py:11
====================================================================================================== short test summary info ======================================================================================================
ERROR tests.py::test_date[patch_datetime0]
ERROR tests.py::test_date[patch_datetime1]
========================================================================================================= 2 errors in 0.01s =========================================================================================================

[The-Compiler]

Remove the fake_date argument and instead use the request fixture and its request.param, like in the example you linked to.

[matteobrv]

My bad, from the example in Indirect parametrization I didn't realize request was actually a fixture. Following your suggestion solved the issue, thank you! I'm just including the working solution as a reference:

import pytest
import datetime

FAKE_DATES = [
    datetime.datetime(1999, 12, 31),
    datetime.datetime(2000, 12, 31)
]

@pytest.fixture
def patch_datetime(monkeypatch, request):

    # [ 1 ] subclass date and override today
    class MyDate(datetime.date):
        @classmethod
        def today(cls):
            return request.param.date()

    # [ 2 ] replace datetime.date with MyDate
    monkeypatch.setattr(datetime, "date", MyDate)

@pytest.mark.parametrize("patch_datetime", FAKE_DATES, indirect=True)
def test_date(patch_datetime):
    print(datetime.date.today())