Pytest run a final test on a shared fixture - pytest

Question

I want to collect information from all my tests, to ensure that I've covered everything, but none of the posts I've come across seem to do this specifically.
If I use e.g. atexit, sessionfinish or other means mentioned when searching for "pytest function after all tests", I seem to lose the ability to use the fixture, and they seem like they're just teardown functions, rather than actual tests.
I want to be able to assert that 1 and 2 are in my fixture list, after running all tests.
import pytest
#pytest.fixture(scope="module")
def fxtr_test_list():
return []
def test_something_1(fxtr_test_list):
fxtr_test_list.append(1)
def test_something_2(fxtr_test_list):
fxtr_test_list.append(2)
#pytest.fixture(scope="session")
def global_check(request, fxtr_test_list):
assert len(fxtr_test_list) == 0 # initial check, should pass
def final_check(request):
assert len(fxtr_test_list) == 0 # final check, should fail
request.addfinalizer(final_check)
return request

Answer 1

You can use fixtures only in tests or other fixtures, so using a fixture in some hook is not possible.
If you don't need a dedicated test, you could just use the fixture itself for testing by making it an autouse-fixture:
import pytest
#pytest.fixture(scope="session")
def fxtr_test_list():
return []
...
#pytest.fixture(scope="session", autouse=True)
def global_check(request, fxtr_test_list):
assert len(fxtr_test_list) == 0 # initial check, should pass
yield
assert len(fxtr_test_list) == 0 # final check, should fail
Note that I changed the scope of the first fixture to "session", otherwise it cannot be used with sesssion-based fixture. Also, I have simplified the second fixture to use the standard setup / yield/ teardown pattern.
This gives you something like:
$ python -m pytest -v test_after_all.py
=================================================
...
collected 2 items
test_after_all.py::test_something_1 PASSED
test_after_all.py::test_something_2 PASSED
test_after_all.py::test_something_2 ERROR
======================================================= ERRORS ========================================================
________________________________________ ERROR at teardown of test_something_2 ________________________________________
request = <SubRequest 'global_check' for <Function test_something_1>>, fxtr_test_list = [1, 2]
#pytest.fixture(scope="session", autouse=True)
def global_check(request, fxtr_test_list):
assert len(fxtr_test_list) == 0 # initial check, should pass
yield
> assert len(fxtr_test_list) == 0 # final check, should fail
E assert 2 == 0
E +2
E -0
...
============================================= 2 passed, 1 error in 0.23s ==============================================
If you really need a dedicated test as the last test, could could use an ordering plugin like pytest-order and mark the test as the last:
#pytest.mark.order(-1)
def test_all_tests(global_check):
...