In pytest, how can I abort the fixture teardown?

Question

Our pytest environment has a lot of fixtures (mostly scope='function' and scope='module') that are doing something of the form:

@pytest.yield_fixture(scope='function')
def some_fixture():
    ... some object initialization ...
    yield some_object
    ... teardown ...

We use the teardown phase of the fixture (after the yield) to delete some resources created specifically for the test.

However, if a test is failing, I don't want the teardown to execute so we will have the resources still exist for further debugging.

For example, here is a common scenario that repeats in all of our testing framework:

@pytest.yield_fixture(scope='function')
def obj_fixture():
    obj = SomeObj.create()
    yield obj
    obj.delete()

def test_obj_some_field(obj_fixture):
    assert obj_fixture.some_field is True

In this case, if the condition in the assert is True I want the obj.delete() to execute. However, if the test is failing, I want pytest to skip the obj.delete() and anything else after the yield.

Thank you.

EDIT I want the process to be done without altering the fixture and the tests code, I prefer an automatic process instead of doing this refactor in our whole testing codebase.

Answer 1

Teardown is intended to be executed independently of whether a test passed or failed.

So I suggest to either write your teardown code such, that it is robust enough to be executed whether the test passed or failed or to add the cleanup to the end of your test, so that it will only be called if no preceding assert failed and if no exception occurred before

Answer 2

Set a class-level flag to indicate pass/fail and check that in your teardown. This is not tested, but should give you the idea::

@pytest.yield_fixture(scope='function')
def obj_fixture():
    obj = SomeObj.create()
    yield obj
    if this.passed:
      obj.delete()

def test_obj_some_field(obj_fixture):
    assert obj_fixture.some_field is True
    this.passed = True

Answer 3

I use a Makefile to execute pytest so had an additional tool at my disposal. I too needed the cleanup of fixtures to happen only on success. I added the cleanup as a second command to my test method in my Makefile.

clean:
    find . | grep -E "(__pycache__|\.pyc|\.pyo)" | xargs rm -rf
    -rm database.db  # the minus here allows this to fail quietly

database:
    python -m create_database

lint:
    black .
    flake8 .

test: clean lint database
    pytest -x -p no:warnings
    rm -rf tests/mock/fixture_dir