fix: Support absolute Windows paths for extensions

Issue mkdocstrings-python#116: mkdocstrings/python#116

Author: pawamoy

src/griffe/extensions/base.py

@@ -8,6 +8,7 @@
 from collections import defaultdict
 from importlib.util import module_from_spec, spec_from_file_location
 from inspect import isclass
+from pathlib import Path
 from typing import TYPE_CHECKING, Any, Sequence, Union
 
 from griffe.agents.nodes import ast_children, ast_kind
@@ -405,8 +406,9 @@ def _load_extension(
         options = {}
 
     # If the import path contains a colon, we split into path and class name.
-    if ":" in import_path:
-        import_path, extension_name = import_path.split(":", 1)
+    colons = import_path.count(":")
+    if colons > 1 or (colons and ":" not in Path(import_path).drive):
+        import_path, extension_name = import_path.rsplit(":", 1)
     else:
         extension_name = None
 

tests/test_extensions.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+from pathlib import Path
 from typing import TYPE_CHECKING, Any
 
 import pytest
@@ -82,6 +83,9 @@ def on_node(self, *, node: ast.AST | ObjectNode) -> None:  # noqa: D102,ARG002
         ExtensionTest(option=0),
         # with class
         ExtensionTest,
+        # with absolute paths (esp. important to test for Windows)
+        Path("tests/test_extensions.py").absolute().as_posix(),
+        Path("tests/test_extensions.py:ExtensionTest").absolute().as_posix(),
     ],
 )
 def test_loading_extensions(extension: str | dict[str, dict[str, Any]] | Extension | type[Extension]) -> None: