test: guard regenerated packages emit pyproject.toml; reset pygen globals

Add tests/unit/test_generated_packaging_files.py which walks all
regenerated packages under tests/generated/ and asserts each one
contains pyproject.toml (and not setup.py), except the explicit
keep-setup-py opt-in package setuppy-authentication-union.

Also reset pygen.codegen.serializers._PACKAGE_FILES and _REGENERATE_FILES
at the start of each spec in run_batch.py. JinjaSerializer._regenerate_setup_py
appends to these module-level globals, and ProcessPoolExecutor reuses
worker processes across specs, so once a worker handled a spec with
keep-setup-py=true, every subsequent spec on that worker would emit
BOTH setup.py and pyproject.toml.

Author: GitHub Copilot

packages/http-client-python/eng/scripts/setup/run_batch.py

@@ -55,6 +55,23 @@ def _coerce(value):
             k: _coerce(v) for k, v in command_args.items() if k not in ["emit-yaml-only"]
         }
 
+        # Reset pygen's module-level _PACKAGE_FILES / _REGENERATE_FILES before each spec.
+        # JinjaSerializer._regenerate_setup_py appends to these globals, and ProcessPoolExecutor
+        # reuses worker processes across specs. Without this reset, once a worker handles a
+        # spec with keep-setup-py=true, every subsequent spec on that worker emits BOTH
+        # setup.py and pyproject.toml.
+        from pygen.codegen import serializers as _serializers
+
+        _serializers._PACKAGE_FILES[:] = [
+            "CHANGELOG.md.jinja2",
+            "dev_requirements.txt.jinja2",
+            "LICENSE.jinja2",
+            "MANIFEST.in.jinja2",
+            "README.md.jinja2",
+        ]
+        _serializers._REGENERATE_FILES.clear()
+        _serializers._REGENERATE_FILES.add("MANIFEST.in")
+
         # Run preprocess and codegen (black is batched at the end for performance)
         preprocess.PreProcessPlugin(output_folder=output_dir, tsp_file=yaml_path, **pygen_args).process()
 

packages/http-client-python/tests/unit/test_generated_packaging_files.py

@@ -0,0 +1,65 @@
+# -------------------------------------------------------------------------
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See License.txt in the project root for
+# license information.
+# --------------------------------------------------------------------------
+"""Verify regenerated test packages emit pyproject.toml, not setup.py.
+
+The Python emitter passes options to pygen via JSON config files. Boolean
+flags arrive as the strings "true"/"false". If those strings are not coerced
+to real booleans before being unpacked as kwargs to pygen, a value like
+keep-setup-py="false" is treated as truthy in Python and pygen emits
+setup.py instead of pyproject.toml. This test guards against that
+regression by walking the regenerated test fixtures.
+"""
+from pathlib import Path
+
+import pytest
+
+# Packages that intentionally opt into setup.py via keep-setup-py=true in
+# eng/scripts/ci/regenerate.ts. They should have setup.py and no pyproject.toml.
+KEEP_SETUP_PY_PACKAGES = {"setuppy-authentication-union"}
+
+_GENERATED_ROOT = Path(__file__).resolve().parents[1] / "generated"
+
+
+def _iter_generated_packages():
+    if not _GENERATED_ROOT.is_dir():
+        return
+    for flavor_dir in sorted(_GENERATED_ROOT.iterdir()):
+        if not flavor_dir.is_dir():
+            continue
+        for pkg_dir in sorted(flavor_dir.iterdir()):
+            if not pkg_dir.is_dir():
+                continue
+            yield flavor_dir.name, pkg_dir
+
+
+@pytest.mark.parametrize(
+    "flavor,pkg_dir",
+    list(_iter_generated_packages()),
+    ids=lambda v: v.name if isinstance(v, Path) else v,
+)
+def test_generated_package_uses_pyproject_toml(flavor, pkg_dir):
+    has_setup_py = (pkg_dir / "setup.py").is_file()
+    has_pyproject = (pkg_dir / "pyproject.toml").is_file()
+
+    if pkg_dir.name in KEEP_SETUP_PY_PACKAGES:
+        assert has_setup_py, f"{flavor}/{pkg_dir.name} should have setup.py (keep-setup-py=true)"
+        assert not has_pyproject, (
+            f"{flavor}/{pkg_dir.name} should NOT have pyproject.toml (keep-setup-py=true)"
+        )
+        return
+
+    assert has_pyproject, (
+        f"{flavor}/{pkg_dir.name} is missing pyproject.toml. "
+        f"This usually means string boolean args (e.g. keep-setup-py=\"false\") "
+        f"were not coerced to real booleans before being passed to pygen. "
+        f"See eng/scripts/setup/run_batch.py."
+    )
+    assert not has_setup_py, (
+        f"{flavor}/{pkg_dir.name} has setup.py but should use pyproject.toml. "
+        f"This usually means string boolean args (e.g. keep-setup-py=\"false\") "
+        f"were not coerced to real booleans before being passed to pygen. "
+        f"See eng/scripts/setup/run_batch.py."
+    )