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fix: add a check to ensure the MRO is correct
Add a check to ensure the MRO (Method Resolution Order) is correct for classes in gitlab.v4.objects when doing type-checking. An example of an incorrect definition: class ProjectPipeline(RESTObject, RefreshMixin, ObjectDeleteMixin): ^^^^^^^^^^ This should be at the end. Correct way would be: class ProjectPipeline(RefreshMixin, ObjectDeleteMixin, RESTObject): Correctly at the end ^^^^^^^^^^ Also fix classes which have the issue.
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""" | ||
Ensure objects defined in gitlab.v4.objects have REST* as last item in class | ||
definition | ||
Original notes by John L. Villalovos | ||
An example of an incorrect definition: | ||
class ProjectPipeline(RESTObject, RefreshMixin, ObjectDeleteMixin): | ||
^^^^^^^^^^ This should be at the end. | ||
Correct way would be: | ||
class ProjectPipeline(RefreshMixin, ObjectDeleteMixin, RESTObject): | ||
Correctly at the end ^^^^^^^^^^ | ||
Why this is an issue: | ||
When we do type-checking for gitlab/mixins.py we make RESTObject or | ||
RESTManager the base class for the mixins | ||
Here is how our classes look when type-checking: | ||
class RESTObject(object): | ||
def __init__(self, manager: "RESTManager", attrs: Dict[str, Any]) -> None: | ||
... | ||
class Mixin(RESTObject): | ||
... | ||
# Wrong ordering here | ||
class Wrongv4Object(RESTObject, RefreshMixin): | ||
... | ||
If we actually ran this in Python we would get the following error: | ||
class Wrongv4Object(RESTObject, Mixin): | ||
TypeError: Cannot create a consistent method resolution | ||
order (MRO) for bases RESTObject, Mixin | ||
When we are type-checking it fails to understand the class Wrongv4Object | ||
and thus we can't type check it correctly. | ||
Almost all classes in gitlab/v4/objects/*py were already correct before this | ||
check was added. | ||
""" | ||
import inspect | ||
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import pytest | ||
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import gitlab.v4.objects | ||
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def test_show_issue(): | ||
"""Test case to demonstrate the TypeError that occurs""" | ||
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class RESTObject(object): | ||
def __init__(self, manager: str, attrs: int) -> None: | ||
... | ||
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class Mixin(RESTObject): | ||
... | ||
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with pytest.raises(TypeError) as exc_info: | ||
# Wrong ordering here | ||
class Wrongv4Object(RESTObject, Mixin): | ||
... | ||
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# The error message in the exception should be: | ||
# TypeError: Cannot create a consistent method resolution | ||
# order (MRO) for bases RESTObject, Mixin | ||
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# Make sure the exception string contains "MRO" | ||
assert "MRO" in exc_info.exconly() | ||
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# Correctly ordered class, no exception | ||
class Correctv4Object(Mixin, RESTObject): | ||
... | ||
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def test_mros(): | ||
"""Ensure objects defined in gitlab.v4.objects have REST* as last item in | ||
class definition. | ||
We do this as we need to ensure the MRO (Method Resolution Order) is | ||
correct. | ||
""" | ||
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failed_messages = [] | ||
for module_name, module_value in inspect.getmembers(gitlab.v4.objects): | ||
if not inspect.ismodule(module_value): | ||
# We only care about the modules | ||
continue | ||
# Iterate through all the classes in our module | ||
for class_name, class_value in inspect.getmembers(module_value): | ||
if not inspect.isclass(class_value): | ||
continue | ||
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# Ignore imported classes from gitlab.base | ||
if class_value.__module__ == "gitlab.base": | ||
continue | ||
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mro = class_value.mro() | ||
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# We only check classes which have a 'gitlab.base' class in their MRO | ||
has_base = False | ||
for count, obj in enumerate(mro, start=1): | ||
if obj.__module__ == "gitlab.base": | ||
has_base = True | ||
base_classname = obj.__name__ | ||
# print(f"\t{obj.__name__}: {obj.__module__}") | ||
if has_base: | ||
filename = inspect.getfile(class_value) | ||
# NOTE(jlvillal): The very last item 'mro[-1]' is always going | ||
# to be 'object'. That is why we are checking 'mro[-2]'. | ||
if mro[-2].__module__ != "gitlab.base": | ||
failed_messages.append( | ||
( | ||
f"class definition for {class_name!r} in file {filename!r} " | ||
f"must have {base_classname!r} as the last class in the " | ||
f"class definition" | ||
) | ||
) | ||
failed_msg = "\n".join(failed_messages) | ||
assert not failed_messages, failed_msg |
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