python-gitlab/tests/meta/test_mro.py at feat/decode-to-string · python-gitlab/python-gitlab · GitHub

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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:

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

import pytest

import gitlab.v4.objects

def test_show_issue() -> None:

"""Test case to demonstrate the TypeError that occurs"""

class RESTObject:

def __init__(self, manager: str, attrs: int) -> None:

...

class Mixin(RESTObject):

...

with pytest.raises(TypeError) as exc_info:

# Wrong ordering here

class Wrongv4Object(RESTObject, Mixin): # type: ignore

...

# The error message in the exception should be:

# TypeError: Cannot create a consistent method resolution

# order (MRO) for bases RESTObject, Mixin

# Make sure the exception string contains "MRO"

assert "MRO" in exc_info.exconly()

# Correctly ordered class, no exception

class Correctv4Object(Mixin, RESTObject):

...

def test_mros() -> None:

"""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.

"""

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

# Ignore imported classes from gitlab.base

if class_value.__module__ == "gitlab.base":

continue

mro = class_value.mro()

# 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__

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

python-gitlab/tests/meta/test_mro.py at feat/decode-to-string · python-gitlab/python-gitlab · GitHub

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