Allow different test output for different Python versions

doc/development_guide/contributor_guide/tests/writing_test.rst

@@ -66,6 +66,27 @@ test runner. The following options are currently supported:
 - "except_implementations": List of python implementations on which the test should not run
 - "exclude_platforms": List of operating systems on which the test should not run
 
+**Different output for different Python versions**
+
+Sometimes the linting result can change between Python releases. In these cases errors can be marked as conditional.
+Supported operators are ``<``, ``<=``, ``>`` and ``>=``.
+
+.. code-block:: python
+
+    def some_func() -> X:  # <3.14:[undefined-variable]
+      ...
+
+    class X: ...
+
+Since the output messages are different, it is necessary to add two separate files for it.
+First ``<test-file-name>.314.txt``, this will include the output messages for ``>=3.14``, i.e. should be empty here.
+Second ``<test-file-name>.txt``, this will be the default for all other Python versions.
+
+.. note::
+
+    This does only work if the code itself is valid in all tested Python versions.
+    For new syntax, use ``min_pyver`` / ``max_pyver`` instead.
+
 **Functional test file locations**
 
 For existing checkers, new test cases should preferably be appended to the existing test file.

doc/whatsnew/fragments/10382.internal

@@ -0,0 +1,3 @@
+Modified test framework to allow for different test output for different Python versions.
+
+Refs #10382

pylint/testutils/functional/test_file.py

@@ -5,8 +5,10 @@
 from __future__ import annotations
 
 import configparser
+import sys
 from collections.abc import Callable
-from os.path import basename, exists, join
+from os.path import basename, exists, join, split
+from pathlib import Path
 from typing import TypedDict
 
 
@@ -99,7 +101,19 @@ def module(self) -> str:
 
     @property
     def expected_output(self) -> str:
-        return self._file_type(".txt", check_exists=False)
+        files = [
+            p.stem
+            for p in Path(self._directory).glob(f"{split(self.base)[-1]}.[0-9]*.txt")
+        ]
+        # pylint: disable-next=bad-builtin
+        current_version = int("".join(map(str, sys.version_info[:2])))
+        output_options = [
+            int(version) for s in files if (version := s.rpartition(".")[2]).isalnum()
+        ]
+        for opt in sorted(output_options, reverse=True):
+            if current_version >= opt:
+                return join(self._directory, f"{self.base}.{opt}.txt")
+        return join(self._directory, self.base + ".txt")
 
     @property
     def source(self) -> str:

tests/functional/ext/typing/unnecessary_default_type_args.py

@@ -3,10 +3,10 @@
 import typing as t
 
 a1: t.Generator[int, str, str]
-a2: t.Generator[int, None, None]
+a2: t.Generator[int, None, None]  # >=3.13:[unnecessary-default-type-args]
 a3: t.Generator[int]
 b1: t.AsyncGenerator[int, str]
-b2: t.AsyncGenerator[int, None]
+b2: t.AsyncGenerator[int, None]  # >=3.13:[unnecessary-default-type-args]
 b3: t.AsyncGenerator[int]
 
 c1: ca.Generator[int, str, str]

tests/functional/ext/typing/unnecessary_default_type_args.rc

@@ -1,3 +1,2 @@
 [main]
-py-version=3.10
 load-plugins=pylint.extensions.typing