Unittest Patch only works on attributes, methods
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Descripción
Bug report
Bug description:
I am having an issue where the patch method from the unittest.mock module is only working when I patch attributes of imported modules in other files. I do not understand if this is an issue of my import patterns or a misunderstanding of how patching works. (I am importing the app code before the patch is able to run).
I devised a test to show how the functionality is confusing me:
In my app code I have the following code
from datetime import date
...
import boto3
...
from common.functions import asodates2datetime
from core.mixins.usecases import ASOUsecaseTools
class foo:
@staticmethod
@ASOUsecaseTools.get_by_name
def bar(self, relevant_date):
client = boto3.client("s3")
today = date.today()
date = asodates2datetime(relevant_date)
And from my test code I can patch in the following way:
@mock.patch("src.aoi.usecases.date")
@mock.patch("src.aoi.usecases.ASOUsecaseTools.get_by_name")
@mock.patch("src.aoi.usecases.asodates2datetime")
@mock.patch("src.aoi.usecases.boto3.client")
def test_foo_gets_bar(self, m_d, m_g, m_a, m_c):
m_d.today.return_value = <date>
m_d.side_effect = lambda *args, **kw: date(*args, **kw)
# more patching of functions here
However, when the test is run, If I set a breakpoint in the bar function and check the value of the patched items, only the patched methods show up as MagicMock
>>> boto3.client
<MagicMock name='client...>
>>> ASOUsecaseTools.get_by_name
<MagicMock name='get_by_name...>
>>> asodates2datetime
<function asodates2datetime...>
>>> date
<class 'datetime.date'>
The thing that confuses me is that I am patching along with how the docs say to patch: https://docs.python.org/3/library/unittest.mock-examples.html#partial-mocking
Also the fact that patched methods work but classes and functions don't indicates that the import structure is not a problem because the imported methods would be overwritten in the same way as the imported classes. It also indicates that the import paths are not incorrect; as the only difference between the patches is the type of object they are patching.
My current workaround is using the freeze package to freeze the date, but I prefer using builtin packages if possible.
CPython versions tested on:
3.9
Operating systems tested on:
macOS
Guía de contribución
Primeros pasos
- Lee el issue completo y luego la guía de contribución del proyecto.
- Comenta en el issue que vas a ocuparte — evita que dos personas hagan lo mismo.
- Haz un fork del repositorio y trabaja en una rama.
- Abre un pull request que haga referencia al número del issue.
Línea de trabajo
Comienza con el reproductor de unittest.mock proporcionado en el issue y compara sus objetivos de patch con la documentación enlazada sobre partial mocking. Verifica el comportamiento en CPython 3.9 y determina después si la diferencia observada es un bug reproducible del intérprete o un malentendido sobre los imports o el patching; una prueba concreta que falle y el comportamiento esperado definirían cuándo se considera terminado.
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Evaluación
- Stack tecnológico
- python
- Área
- testing-qa
- Tipo de issue
- Error
- Dificultad
- 5/5
- Tiempo estimado
- Más de una semana
- Estado de actividad
- Estancado
- Claridad
- Necesita aclaración
- Aptitud para principiantes
- 25/100