What I have found out while debugging:
When thenode.ancestors(recurs=False) function is called in diagrams.py lines 213-219

# inheritance linkforpar_nodeinnode.ancestors(recurs=False):try:par_obj=self.object_from_node(par_node)self.add_relationship(obj,par_obj,"specialization")exceptKeyError:continue

the ancestors are not extracted correctly as the cached InferenceContext maps the statement of the name of the base classes to "Uninferable"

As I really do not know what is going on there in astroid, my quick and dirty solution would be to extract the correct base classes via their name:

# inheritance linksforpar_nodeinnode.bases:# Name nodes are used for simple types, e.g. class A(B):ifisinstance(par_node,astroid.Name):try:par_obj=self.classe(par_node.name)self.add_relationship(obj,par_obj,"specialization")exceptKeyError:continue# Subscript is used for generic types, e.g. class A(Generic[T]):ifisinstance(par_node,astroid.Subscript):try:par_obj=self.classe(par_node.value.name)self.add_relationship(obj,par_obj,"specialization")exceptKeyError:continue

I have pushed this simple fix tohttps://github.com/ANTICIPATE-GmbH/pylint/tree/fix/7686/extract-inheritance-relations-correctly. Note that with this fix, all test cases complete without issues.

🤖 According to the primer, this change hasno effect on the checked open source code. 🤖🎉

This comment was generated for commitd99f984

I tried it out locally and I quite like it.
As mentioned I would like to expand on this to also include a functional test harness for package diagrams.
There already exists some test data undertests/pyreverse/functional/package_diagrams, which however does not build upontest_pyreverse_functional.py to collect the test data.

With your change and some very minor modifications, we can move these files into the newtests/pyreverse/functional/packages directory (we can do that in a follow up PR, just want to note down what I did locally):

diff --git a/pylint/testutils/pyreverse.py b/pylint/testutils/pyreverse.pyindex 9e6647183..03840944e 100644--- a/pylint/testutils/pyreverse.py+++ b/pylint/testutils/pyreverse.py@@ -72,6 +72,7 @@ class TestFileOptions(TypedDict):     source_roots: list[str]     output_formats: list[str]     command_line_args: list[str]+    diagram_type: str   class FunctionalPyreverseTestfile(NamedTuple):@@ -150,4 +151,5 @@ def _read_config(config_file: Path) -> TestFileOptions:         "command_line_args": shlex.split(             config.get("testoptions", "command_line_args", fallback="")         ),+        "diagram_type": config.get("testoptions", "diagram_type", fallback="classes"),     }diff --git a/tests/pyreverse/test_pyreverse_functional.py b/tests/pyreverse/test_pyreverse_functional.pyindex beeb0330b..e02574463 100644--- a/tests/pyreverse/test_pyreverse_functional.py+++ b/tests/pyreverse/test_pyreverse_functional.py@@ -86,5 +86,5 @@ def test_packages(test_package: FunctionalPyreverseTestfile, tmp_path: Path) ->             Run(args)         assert sys_exit.value.code == 0         assert output_file.read_text(encoding="utf8") == (-            tmp_path / f"classes.{output_format}"+            tmp_path / f"{test_package.options['diagram_type']}.{output_format}"         ).read_text(encoding="utf8")

This essentially just adds an option to the .rc file so that the author can specify if his tests generate a class or a package diagram.

As a next step regarding this MR, I think we can simplify the code a bit. For example, theget_functional_test_files() andget_functional_test_packages() in thetestutils package share some common logic to handle the.rc files, and thetest_class_diagrams() andtest_packages() intest_pyreverse_functional as well.

For the suggested fix, I am hesitant to judge if this is the best way to fix it, as I currently don't find the time to work myself back intoastroid and debug this issue to understand what is going on. Maybe one of the other maintainers has time to take a look (maybe@nickdrozd?) , otherwise I have to ask for your patience until I can take the time to properly look at it.