I'm a bit late to the party, and really only reiterating what has already been said, but of the two examples (original and your rewrite, I prefer the original. I think as a general rule, we tend to use the assert_called_once, etc with mocks butt he asserts with non-mocked variables.
I am all for more documentation, but I'd have a slight preference towards keeping the existing structure. - ferruzzi ________________________________ From: Kyungjun Lee <kyungjunlee...@gmail.com> Sent: Tuesday, July 8, 2025 2:13 AM To: dev@airflow.apache.org Subject: RE: [EXT] [DISCUSS] Consistent test assertion style: pytest-native vs unittest-style CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe. AVERTISSEMENT: Ce courrier électronique provient d’un expéditeur externe. Ne cliquez sur aucun lien et n’ouvrez aucune pièce jointe si vous ne pouvez pas confirmer l’identité de l’expéditeur et si vous n’êtes pas certain que le contenu ne présente aucun risque. Thank you Ash and Amogh Desai for your insights and explanations. The information you shared has been incredibly helpful and is contributing a lot to my growth. 2025년 7월 8일 (화) 오후 2:54, Amogh Desai <amoghdesai....@gmail.com>님이 작성: > Agreed, I personally also find the current way to be easier to read and in > most > cases we want to assert if "something" was called, irrespective of the > order it was > called in. So the dedicated function based way works well for me. > > If I want to test a order, I'd rather call parts of code that I want to > test explicitly and assert > on them. > > > This happens because the mock object is not properly recognized as a mock > instance at type-checking time, which might confuse some contributors, > especially new ones relying on type hints or static analysis tools. > > Regarding this, I'd say you can either cast mocks to their types as one > way: > `mock_http_run: MagicMock = mock_http_run` -- give or take, or use > `autospec` to make the mock reflect the signature of the object? Check out: > https://docs.python.org/3/library/unittest.mock.html#autospeccing > > Thanks & Regards, > Amogh Desai > > > On Mon, Jul 7, 2025 at 6:13 PM Ash Berlin-Taylor <a...@apache.org> wrote: > > > def test_get_account(self, mock_paginate: Mock, mock_http_run: Mocj, > > conn_id, account_id): > > > > > > Might fix that? IDEs in general do not cope well with purest tests, and > > are missing context on what most of the variables are, be it > parameterised > > values or fixture values, so this isn’t a problem that is unique to > mocks. > > > > > On 7 Jul 2025, at 12:47, Kyungjun Lee <kyungjunlee...@gmail.com> > wrote: > > > > > > I'd like to follow up on our previous discussion about pytest-native vs > > > unittest-style assertions. > > > > > > While working on the following test case: > > > > > > ```python > > > > > > @pytest.mark.parametrize( > > > argnames="conn_id, account_id", > > > argvalues=[(ACCOUNT_ID_CONN, None), (NO_ACCOUNT_ID_CONN, > ACCOUNT_ID)], > > > ids=["default_account", "explicit_account"], > > > ) > > > @patch.object(DbtCloudHook, "run") > > > @patch.object(DbtCloudHook, "_paginate") > > > def test_get_account(self, mock_paginate, mock_http_run, conn_id, > > > account_id): > > > hook = DbtCloudHook(conn_id) > > > hook.get_account(account_id=account_id) > > > > > > assert hook.method == "GET" > > > > > > _account_id = account_id or DEFAULT_ACCOUNT_ID > > > hook.run.assert_called_once_with( > > > endpoint=f"api/v2/accounts/{_account_id}/", data=None, > > > extra_options=None > > > ) > > > hook._paginate.assert_not_called() > > > > > > ``` > > > > > > My IDE shows a warning: > > > Cannot find reference 'assert_called_once_with' in 'function'. > > > > > > This happens because the mock object is not properly recognized as a > mock > > > instance at type-checking time, which might confuse some contributors, > > > especially new ones relying on type hints or static analysis tools. > > > > > > I realized that this aspect of mock handling might be missing from our > > > previous discussions. I wanted to bring it up as part of the broader > > > conversation about test styles—particularly how we balance IDE/tooling > > > support with readability and style consistency. > > > > > > Curious to hear your thoughts on this! > > > > > > @ash @potiuk > > > > > > 2025년 7월 6일 (일) 오후 8:09, Kyungjun Lee <kyungjunlee...@gmail.com>님이 작성: > > > > > >> Thank you @Potiuk for pointing out the intent behind the “one assert > per > > >> test” principle, and @ash for highlighting how using dedicated mock > > assert > > >> functions can make the code easier to read and understand. These were > > >> perspectives I hadn’t fully considered, and I really appreciate you > > sharing > > >> them. > > >> > > >> Thanks to your input, I was able to read more materials and broaden my > > >> thinking on the topic. That said, my original focus was more on the > idea > > >> that sticking to plain assert statements lowers the entry barrier for > > new > > >> contributors—because they don’t have to learn multiple assertion > styles. > > >> > > >> Still, as @Potiuk mentioned, I’ll put more thought into making the > > testing > > >> guidelines clearer and more concrete—especially since that helps > > AI-based > > >> tools as well 😄 > > >> > > >> For reference, here’s one of the articles I read: > > >> https://medium.com/@kentbeck_7670/test-desiderata-94150638a4b3 > > >> > > >> Thank you to everyone who took part in this discussion. > > >> > > >> 2025년 7월 6일 (일) 오후 3:42, Ash Berlin-Taylor <a...@apache.org>님이 작성: > > >> > > >>> I personally find the dedicated functions way easier to read the > intent > > >>> behind, it’s one function/statement vs 3. More so when you don’t care > > about > > >>> the order of calls, just that something was called (where to do this > > >>> manually we’d need to reimplement the helper function) > > >>> > > >>> Additionally pytest already rewrites those to have nicer error > > messages, > > >>> but the dedicated mock assert finding are much easier to read the > code > > and > > >>> understand the intent to me, so I’i am for staying with the dedicated > > >>> assert functions > > >>> > > >>> -ash > > >>> > > >>>> On 5 Jul 2025, at 13:30, Kyungjun Lee <kyungjunlee...@gmail.com> > > wrote: > > >>>> > > >>>> I’ve learned a lot of things I didn’t know before. > > >>>> Thank you so much for all your help — I really appreciate it. > > >>>> I’ll get started on this right away! > > >>>> > > >>>> 2025년 7월 5일 (토) 오후 9:18, Jarek Potiuk <ja...@potiuk.com>님이 작성: > > >>>> > > >>>>>> Haha ... I'm curious — which part sounded like ChatGPT style? > > >>>>> English isn't my first language, so I did get a little help from > it. > > >>>>> > > >>>>> That whole paragraph :) . > > >>>>> > > >>>>>>> Sure! Since you asked for how the test *should* be written, I > took > > >>> the > > >>>>> opportunity to clean it up using a more pytest-native style while > > also > > >>>>> fixing the mock order issue. > > >>>>> > > >>>>> "Sure! Since you asked ..." sounds like an AI bot. > > >>>>> > > >>>>>> That got me thinking — what do you think about adding a guideline > > >>>>> document > > >>>>> for writing tests, similar to how we have a coding style guide? > > >>>>> > > >>>>> Absolutely - we already have some "seed' of it "Writing tests" > > >>> chapter in > > >>>>> contributing guideline, but we could definitely make it more > > detailed. > > >>>>> > > >>>>> > > >>>>> > > >>> > > > https://github.com/apache/airflow/blob/main/contributing-docs/testing/unit_tests.rst#writing-unit-tests > > >>>>> > > >>>>> And - speaking of AI - this is becoming more and more important to > > >>> describe > > >>>>> any common rules we have and context - so that using Agentic AI > > yields > > >>>>> better results. Kaxil already added > > >>>>> https://github.com/apache/airflow/blob/main/AGENTS.md which > > describes > > >>>>> context for coding agents lile Codex - and we could improve it and > > link > > >>>>> more docs from our repo if they get more of our agreed > "conventions" > > - > > >>> then > > >>>>> Agents would get it as context and their generated code would be > > >>> consistent > > >>>>> with what we describe there. > > >>>>> > > >>>>> In a way - I think having a good documentation on processes, tools > > and > > >>>>> conventions was always something I've been after, but with the > > Agentic > > >>>>> workflows it might significantly boost the quality of generated > code > > >>> if we > > >>>>> have more of those conventions and guidelines described. > > >>>>> > > >>>>> So .... ABSOLUTELY ... the more we describe in there, the better. > And > > >>> we > > >>>>> have no more excuse that "anyhow no-one reads it" - because the > > coding > > >>>>> agents WILL be reading it and acting accordingly. So I think this > is > > a > > >>> very > > >>>>> good investment to make. > > >>>>> > > >>>>> J. > > >>>>> > > >>>>> > > >>>>> > > >>>>> > > >>>>> > > >>>>>> On Sat, Jul 5, 2025 at 2:07 PM Kyungjun Lee < > > kyungjunlee...@gmail.com > > >>>> > > >>>>>> wrote: > > >>>>>> > > >>>>>> Haha ... I'm curious — which part sounded like ChatGPT style? > > >>>>>> English isn't my first language, so I did get a little help from > it. > > >>>>>> > > >>>>>> But thank you — I actually learned something new from your > comment! > > >>>>>> That got me thinking — what do you think about adding a guideline > > >>>>> document > > >>>>>> for writing tests, similar to how we have a coding style guide? It > > >>> might > > >>>>>> help ensure consistency across the Airflow codebase when it comes > to > > >>>>>> testing styles as well. > > >>>>>> > > >>>>>> 2025년 7월 5일 (토) 오후 8:52, Jarek Potiuk <ja...@potiuk.com>님이 작성: > > >>>>>> > > >>>>>>> But of course - i'd love to hear what others think - it's not a > > "very > > >>>>>>> strong" opinion. > > >>>>>>> > > >>>>>>> On Sat, Jul 5, 2025 at 1:48 PM Jarek Potiuk <ja...@potiuk.com> > > >>> wrote: > > >>>>>>> > > >>>>>>>> Cool. That's what I wanted to see. > > >>>>>>>> > > >>>>>>>> By the way - not that there's anything wrong - but was the > answer > > >>>>>> written > > >>>>>>>> by AI initially ? The first paragraph looks suspiciously like > Chat > > >>>>> GPT > > >>>>>>>> answer :D ? > > >>>>>>>> > > >>>>>>>> Comment from my side: I personally prefer the original style. > It's > > >>>>> more > > >>>>>>>> concise and it is easier to read - you see as if the call was > > >>>>> actually > > >>>>>>>> written down. Also this is quite a bit too many assertions in > the > > >>>>>> second > > >>>>>>>> case and it takes a lot of mental effort to understand what > > actually > > >>>>> is > > >>>>>>>> being asserted. > > >>>>>>>> > > >>>>>>>> There is a "school" of writing unit tests that every test should > > >>> have > > >>>>>> ONE > > >>>>>>>> assertion only. Always. I think it is a bit extreme, and I do > not > > >>>>>> follow > > >>>>>>> it > > >>>>>>>> myself but I think it is also a kind of good direction to have > -> > > >>> the > > >>>>>>> fewer > > >>>>>>>> assertions you have in your test, the better (I think). > > >>>>>>>> > > >>>>>>>> I think tests should be mostly optimized for easiness of reading > > and > > >>>>>>>> understanding what is being tested - and it's just not that easy > > in > > >>>>> the > > >>>>>>>> second case. > > >>>>>>>> > > >>>>>>>> J. > > >>>>>>>> > > >>>>>>>> > > >>>>>>>> > > >>>>>>>> On Sat, Jul 5, 2025 at 1:39 PM Kyungjun Lee < > > >>>>> kyungjunlee...@gmail.com> > > >>>>>>>> wrote: > > >>>>>>>> > > >>>>>>>>> Sure! Since you asked for how the test *should* be written, I > > took > > >>>>> the > > >>>>>>>>> opportunity to clean it up using a more pytest-native style > while > > >>>>> also > > >>>>>>>>> fixing the mock order issue. > > >>>>>>>>> > > >>>>>>>>> Here’s the updated test: > > >>>>>>>>> > > >>>>>>>>> ```python > > >>>>>>>>> > > >>>>>>>>> @pytest.mark.parametrize( > > >>>>>>>>> argnames="conn_id, account_id", > > >>>>>>>>> argvalues=[(ACCOUNT_ID_CONN, None), (NO_ACCOUNT_ID_CONN, > > >>>>>>> ACCOUNT_ID)], > > >>>>>>>>> ids=["default_account", "explicit_account"], > > >>>>>>>>> ) > > >>>>>>>>> @patch.object(DbtCloudHook, "run") > > >>>>>>>>> @patch.object(DbtCloudHook, "_paginate") > > >>>>>>>>> def test_get_account(self, mock_paginate, mock_http_run, > conn_id, > > >>>>>>>>> account_id): > > >>>>>>>>> hook = DbtCloudHook(conn_id) > > >>>>>>>>> hook.get_account(account_id=account_id) > > >>>>>>>>> > > >>>>>>>>> assert hook.method == "GET" > > >>>>>>>>> > > >>>>>>>>> expected_account_id = account_id or DEFAULT_ACCOUNT_ID > > >>>>>>>>> > > >>>>>>>>> assert mock_http_run.call_count == 1 > > >>>>>>>>> assert mock_http_run.call_args.args == () > > >>>>>>>>> assert mock_http_run.call_args.kwargs == { > > >>>>>>>>> "endpoint": f"api/v2/accounts/{expected_account_id}/", > > >>>>>>>>> "data": None, > > >>>>>>>>> "extra_options": None, > > >>>>>>>>> } > > >>>>>>>>> > > >>>>>>>>> assert mock_paginate.call_count == 0 > > >>>>>>>>> > > >>>>>>>>> ``` > > >>>>>>>>> Why I chose this style: > > >>>>>>>>> > > >>>>>>>>> - > > >>>>>>>>> > > >>>>>>>>> *Mock verification using assert*: Instead of > > >>>>>>>>> mock.assert_called_once_with(...), I used call_count and > > >>>>> call_args. > > >>>>>>>>> This > > >>>>>>>>> approach aligns better with pytest’s idioms and produces > > cleaner, > > >>>>>>> more > > >>>>>>>>> readable error messages when assertions fail. > > >>>>>>>>> - > > >>>>>>>>> > > >>>>>>>>> *Explicit verification*: Using call_args.args and > > >>>>> call_args.kwargs > > >>>>>>>>> makes > > >>>>>>>>> the test behavior very explicit, which helps with debugging > and > > >>>>>>>>> understanding the exact calls made. > > >>>>>>>>> - > > >>>>>>>>> > > >>>>>>>>> *Decorator order matching argument order*: As @patch > decorators > > >>>>>> apply > > >>>>>>>>> from the bottom up, the argument order has been corrected to > > >>>>> match > > >>>>>> ( > > >>>>>>>>> mock_paginate first, then mock_http_run). > > >>>>>>>>> > > >>>>>>>>> Let me know if you'd like to follow a slightly different > > convention > > >>>>> — > > >>>>>>>>> happy > > >>>>>>>>> to adjust! > > >>>>>>>>> > > >>>>>>>>> I was lucky to have the chance to explain this while fixing a > > >>>>> related > > >>>>>>> bug. > > >>>>>>>>> You can refer to the changes in this PR: > > >>>>>>>>> https://github.com/apache/airflow/pull/52905 > > >>>>>>>>> > > >>>>>>>>> > > >>>>>>>>> > > >>>>>>>>> 2025년 7월 5일 (토) 오후 8:09, Jarek Potiuk <ja...@potiuk.com>님이 작성: > > >>>>>>>>> > > >>>>>>>>>> Just post how you think the test should be written :) > > >>>>>>>>>> > > >>>>>>>>>> On Sat, Jul 5, 2025 at 1:08 PM Jarek Potiuk <ja...@potiuk.com > > > > >>>>>> wrote: > > >>>>>>>>>> > > >>>>>>>>>>> I already mentioned it in slack - but how would you propose > to > > >>>>>>> rewrite > > >>>>>>>>>> the > > >>>>>>>>>>> "mixed" case to be more consistent ? > > >>>>>>>>>>> > > >>>>>>>>>>> On Sat, Jul 5, 2025 at 12:47 PM Kyungjun Lee < > > >>>>>>>>> kyungjunlee...@gmail.com> > > >>>>>>>>>>> wrote: > > >>>>>>>>>>> > > >>>>>>>>>>>> Hi all, > > >>>>>>>>>>>> > > >>>>>>>>>>>> While reviewing and contributing to Airflow tests, I’ve > > noticed > > >>>>>> an > > >>>>>>>>>>>> inconsistency in how assertions are written. Some tests use > > >>>>>>>>>>>> `unittest`-style assertions like > > >>>>> `mock.assert_called_once_with`, > > >>>>>>>>> while > > >>>>>>>>>>>> others use plain `assert` statements in the `pytest` style. > > >>>>>>>>>>>> > > >>>>>>>>>>>> Here's an example of a test using the mixed style: > > >>>>>>>>>>>> > > >>>>>>>>>>>> ```python > > >>>>>>>>>>>> @pytest.mark.parametrize( > > >>>>>>>>>>>> argnames="conn_id, account_id", > > >>>>>>>>>>>> argvalues=[(ACCOUNT_ID_CONN, None), (NO_ACCOUNT_ID_CONN, > > >>>>>>>>>> ACCOUNT_ID)], > > >>>>>>>>>>>> ids=["default_account", "explicit_account"], > > >>>>>>>>>>>> ) > > >>>>>>>>>>>> @patch.object(DbtCloudHook, "run") > > >>>>>>>>>>>> @patch.object(DbtCloudHook, "_paginate") > > >>>>>>>>>>>> def test_get_account(self, mock_http_run, mock_paginate, > > >>>>> conn_id, > > >>>>>>>>>>>> account_id): > > >>>>>>>>>>>> hook = DbtCloudHook(conn_id) > > >>>>>>>>>>>> hook.get_account(account_id=account_id) > > >>>>>>>>>>>> > > >>>>>>>>>>>> assert hook.method == "GET" > > >>>>>>>>>>>> > > >>>>>>>>>>>> _account_id = account_id or DEFAULT_ACCOUNT_ID > > >>>>>>>>>>>> hook.run.assert_called_once_with( > > >>>>>>>>>>>> endpoint=f"api/v2/accounts/{_account_id}/", data=None, > > >>>>>>>>>>>> extra_options=None > > >>>>>>>>>>>> ) > > >>>>>>>>>>>> hook._paginate.assert_not_called() > > >>>>>>>>>>>> ``` > > >>>>>>>>>>>> > > >>>>>>>>>>>> In IDEs and type-checkers (like PyCharm or MyPy), this > > >>>>> sometimes > > >>>>>>>>> causes > > >>>>>>>>>>>> weak warnings > > >>>>>>>>>>>> > > >>>>>>>>>>>> ``` > > >>>>>>>>>>>> > > >>>>>>>>>>>> Cannot find reference 'assert_called_once_with' in > 'function' > > >>>>>>>>>>>> > > >>>>>>>>>>>> ``` > > >>>>>>>>>>>> > > >>>>>>>>>>>> This could confuse newcomers or contributors unfamiliar with > > >>>>>>> mocking > > >>>>>>>>>>>> behavior or type limitations in dynamic typing. > > >>>>>>>>>>>> > > >>>>>>>>>>>> To improve clarity and accessibility for > > >>>>> contributors—especially > > >>>>>>>>> those > > >>>>>>>>>> new > > >>>>>>>>>>>> to the project—I’d like to propose *moving toward consistent > > >>>>> use > > >>>>>> of > > >>>>>>>>>> plain > > >>>>>>>>>>>> assert statements* for test validations wherever possible. > > >>>>>>>>>>>> > > >>>>>>>>>>>> *Proposed Benefits*: > > >>>>>>>>>>>> > > >>>>>>>>>>>> - > > >>>>>>>>>>>> > > >>>>>>>>>>>> Easier onboarding for first-time contributors > > >>>>>>>>>>>> - > > >>>>>>>>>>>> > > >>>>>>>>>>>> Better IDE support and fewer confusing warnings > > >>>>>>>>>>>> - > > >>>>>>>>>>>> > > >>>>>>>>>>>> More consistent and readable test style across the project > > >>>>>>>>>>>> > > >>>>>>>>>>>> I'd love to hear your thoughts on whether this direction > makes > > >>>>>>> sense > > >>>>>>>>> for > > >>>>>>>>>>>> the project. If agreed, I’d also be happy to help align > > >>>>> existing > > >>>>>>>>> tests > > >>>>>>>>>>>> gradually. > > >>>>>>>>>>>> > > >>>>>>>>>>>> Thanks! > > >>>>>>>>>>>> Kyungjun Lee > > >>>>>>>>>>>> > > >>>>>>>>>>> > > >>>>>>>>>> > > >>>>>>>>> > > >>>>>>>> > > >>>>>>> > > >>>>>> > > >>>>> > > >>> > > >>> > > >>> --------------------------------------------------------------------- > > >>> To unsubscribe, e-mail: dev-unsubscr...@airflow.apache.org > > >>> For additional commands, e-mail: dev-h...@airflow.apache.org > > >>> > > >>> > > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: dev-unsubscr...@airflow.apache.org > > For additional commands, e-mail: dev-h...@airflow.apache.org > > > > >
