Question: writing a plugin with a fixture that can access its plugin instance properties

[westhomas]

Sample code:

class CollectorPlugin:
    def __init__(self, group_name):
        self.group_name = group_name
        self.collected = []

    @pytest.fixture
    def capture_logs(self, request):
        
        #self is an instance of test_method1 NOT of CollectorPlugin?
        print(self.group_name)


collector_plugin = CollectorPlugin("test")

returncode = pytest.main(
    args,
    plugins=[collector_plugin]
)

def test_method1(capture_logs):
    assert True

The capture_logs fixture can't seem to access the plugin's instance object self.

How can I pass some data to the fixture from the plugin?

[RonnyPfannschmidt]

please show the exception/error

[westhomas]

Sorry for the poor example. Here's a better one:

# test.py
import unittest
import pytest

# Tests
def test_foo(info):
    print("test_foo")
    assert True

def test_bar():
    print("test_bar")
    assert True

class Baz(unittest.TestCase):
    def test_baz(self):
        print("test_baz")
        assert True


# Execute Tests
def main():

    class MyPlugin(object):
        def __init__(self, data):
            self.data = data

        @pytest.fixture(autouse=True)
        def info(self, request):
            print("fixture: ", self.data)

    myplugin = MyPlugin('information')

    pytest.main(["test.py", "-s"], plugins=[myplugin])

if __name__ == "__main__":
    main()

test_baz fails because self is no longer an instance of MyPlugin but an instance of Baz.

$ python test.py
==================================================================== test session starts =====================================================================
platform darwin -- Python 3.6.0, pytest-3.0.6, py-1.4.32, pluggy-0.4.0
rootdir: /Users/wes/work/pytest, inifile:
collected 3 items

test.py fixture:  information
test_foo
.fixture:  information
test_bar
.E

=========================================================================== ERRORS ===========================================================================
_______________________________________________________________ ERROR at setup of Baz.test_baz _______________________________________________________________

self = <test.Baz testMethod=test_baz>, request = <SubRequest 'info' for <TestCaseFunction 'test_baz'>>

    @pytest.fixture(autouse=True)
    def info(self, request):
>       print("fixture: ", self.data)
E       AttributeError: 'Baz' object has no attribute 'data'

test.py:28: AttributeError
============================================================= 2 passed, 1 error in 0.04 seconds ==============================================================

What I need is someway for the fixture to get a reference to MyPlugin while executing. Is there someway to do that via the configuration context? i.e. item.config.pluginmanager.getplugin('some_plugin')

[RonnyPfannschmidt]

at first glance that looks like a bug, self should not be Baz there

[westhomas]

I'm trying to dig into this issue in the pytest code, but it's over my head at this point.

Could you help me find the relevant tests or entry points to maybe see about resolving this issue?

[RonnyPfannschmidt]

@westhomas im not too familiar with the inner details either, @hpk42 and @nicoddemus worked on it more deply

[westhomas]

@hpk42 @nicoddemus If this isn't a high priority issue, any ideas on a work around?

I need to get access to a Fixture's instance attributes from within the test function, but it doesn't work in my use case. See #2270 (comment)

[RonnyPfannschmidt]

,request.config.pluginmanager.get_plugin might help

[nicoddemus]

Sorry @westhomas this went under the radar.

I think @RonnyPfannschmidt's suggestion is on point!

[westhomas]

Great! Thanks!

Here's my final that seems to work great:

# test.py
import unittest
import pytest

# Tests
def test_foo(info):
    print("test_foo")
    assert True

def test_bar():
    print("test_bar")
    assert True

class Baz(unittest.TestCase):
    def test_baz(self):
        print("test_baz")
        assert True


# Execute Tests
def main():

    class MyPlugin(object):
        def __init__(self, data):
            self.__name__ = "myplugin"   # <==== give it a name so you can reference it in get_plugin
            self.data = data

        @pytest.fixture(autouse=True)
        def info(self, request):
            test = request.config.pluginmanager.get_plugin('myplugin')
            print("fixture: ", test.data)

    myplugin = MyPlugin('information')

    pytest.main(["test.py", "-s"], plugins=[myplugin])

if __name__ == "__main__":
    main()