Python: Preserve native changed-package path semantics

.github/workflows/python-tests.yml

@@ -54,6 +54,10 @@ jobs:
         run: uv run poe test -A --junitxml=pytest.xml
         working-directory: ./python
 
+      - name: Run workspace script routing tests
+        run: uv run --locked --group dev --group tool-runtime python -m pytest scripts/tests --import-mode=importlib -q
+        working-directory: ./python
+
       # Surface failing tests
       - name: Surface failing tests
         if: always()

python/scripts/run_tasks_in_changed_packages.py

@@ -6,6 +6,7 @@
 from pathlib import Path
 
 from rich import print
+
 from scripts.task_runner import build_work_items, discover_projects, run_tasks
 
 # Tasks that need to run in all packages when core changes (type info propagates)
@@ -24,15 +25,15 @@ def get_changed_packages(
     core_package_changed = False
 
     for file_path in changed_files:
-        # Strip 'python/' prefix if present (when git diff is run from repo root)
-        file_path_str = str(file_path)
-        if file_path_str.startswith("python/"):
-            file_path_str = file_path_str[7:]  # Remove 'python/' prefix
+        # Strip the repository prefix using native separators, preserving POSIX filenames.
+        file_path_obj = Path(file_path)
+        if file_path_obj.parts and file_path_obj.parts[0] == "python":
+            file_path_obj = Path(*file_path_obj.parts[1:])
 
         # Convert to absolute path if relative
-        abs_path = Path(file_path_str)
+        abs_path = file_path_obj
         if not abs_path.is_absolute():
-            abs_path = workspace_root / file_path_str
+            abs_path = workspace_root / file_path_obj
 
         # Check which package this file belongs to
         for project in projects:

python/scripts/tests/test_changed_package_native_paths.py

@@ -0,0 +1,116 @@
+# Copyright (c) Microsoft. All rights reserved.
+
+"""Exercise native changed-package paths and task routing."""
+
+from __future__ import annotations
+
+import os
+from pathlib import Path
+from unittest.mock import Mock
+
+import pytest
+
+from scripts import run_tasks_in_changed_packages as runner
+
+PROJECTS = [Path("packages/core"), Path("packages/redis")]
+
+
+@pytest.fixture
+def workspace(tmp_path: Path) -> Path:
+    root = tmp_path / "python"
+    root.mkdir()
+    return root
+
+
+@pytest.mark.parametrize("package", ["core", "redis"])
+@pytest.mark.parametrize("spelling", ["repo-forward", "repo-native", "dot-forward", "dot-native"])
+def test_repository_relative_path_selects_package(workspace: Path, package: str, spelling: str) -> None:
+    relative = Path("python") / "packages" / package / "example.py"
+    paths = {
+        "repo-forward": relative.as_posix(),
+        "repo-native": str(relative),
+        "dot-forward": "./" + relative.as_posix(),
+        "dot-native": "." + os.sep + str(relative),
+    }
+
+    assert runner.get_changed_packages(PROJECTS, [paths[spelling]], workspace) == (
+        {Path("packages") / package},
+        package == "core",
+    )
+
+
+@pytest.mark.parametrize("spelling", ["workspace-forward", "workspace-native", "absolute"])
+def test_existing_path_forms_keep_selecting_core(workspace: Path, spelling: str) -> None:
+    relative = Path("packages/core/example.py")
+    paths = {
+        "workspace-forward": relative.as_posix(),
+        "workspace-native": str(relative),
+        "absolute": str(workspace / relative),
+    }
+
+    assert runner.get_changed_packages(PROJECTS, [paths[spelling]], workspace) == ({PROJECTS[0]}, True)
+
+
+def test_unrelated_path_stays_unselected(workspace: Path) -> None:
+    assert runner.get_changed_packages(PROJECTS, ["dotnet/example.cs"], workspace) == (set(), False)
+
+
+@pytest.mark.skipif(os.name == "nt", reason="Backslash is a filename character on POSIX.")
+def test_literal_backslash_package_keeps_its_identity(workspace: Path) -> None:
+    literal_package = Path(r"packages/core\notes")
+    projects = [*PROJECTS, literal_package]
+    file_path = workspace / literal_package / "example.py"
+    file_path.parent.mkdir(parents=True)
+    file_path.write_text("", encoding="utf-8")
+
+    assert runner.get_changed_packages(projects, [str(file_path)], workspace) == ({literal_package}, False)
+    assert runner.get_changed_packages(projects, [str(Path("python") / literal_package / "example.py")], workspace) == (
+        {literal_package},
+        False,
+    )
+
+
+@pytest.mark.skipif(os.name != "nt", reason="UNC paths use native Windows semantics.")
+def test_absolute_unc_path_keeps_selecting_core() -> None:
+    workspace = Path(r"\\server\share\repo\python")
+    file_path = workspace / PROJECTS[0] / "example.py"
+
+    assert runner.get_changed_packages(PROJECTS, [str(file_path)], workspace) == ({PROJECTS[0]}, True)
+
+
+@pytest.mark.parametrize("package", ["core", "redis"])
+def test_cli_native_path_routes_local_and_type_tasks(
+    workspace: Path, package: str, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    (workspace / "pyproject.toml").write_text(
+        '[tool.uv.workspace]\nmembers = ["packages/core", "packages/redis"]\n', encoding="utf-8"
+    )
+    for project in PROJECTS:
+        directory = workspace / project
+        directory.mkdir(parents=True)
+        (directory / "pyproject.toml").write_text(
+            '[tool.poe.tasks]\nlint = "echo unused"\npyright = "echo unused"\n', encoding="utf-8"
+        )
+    monkeypatch.chdir(workspace)
+    monkeypatch.setattr(runner, "__file__", str(workspace / "scripts/run_tasks_in_changed_packages.py"))
+    monkeypatch.setattr(
+        "sys.argv",
+        [
+            "run_tasks_in_changed_packages.py",
+            "lint",
+            "pyright",
+            "--files",
+            "." + os.sep + str(Path("python/packages") / package / "example.py"),
+            "--seq",
+        ],
+    )
+    run_tasks = Mock()
+    monkeypatch.setattr(runner, "run_tasks", run_tasks)
+
+    runner.main()
+
+    selected = Path("packages") / package
+    typed = PROJECTS if package == "core" else [selected]
+    run_tasks.assert_called_once_with(
+        [(selected, "lint"), *((project, "pyright") for project in typed)], workspace, sequential=True
+    )