test: Stop importing fixer as a module

The dependabot-grpc-fixer is meant to be exercised as a script, not
through a dynamically imported module. Run the remaining tests via
runpy so they cover the supported entrypoint instead of the script
internals.

Drop the replace_range() unit test and the shared module loader to
reduce coupling to implementation details while keeping the existing
script-level coverage.

Signed-off-by: Leandro Lucarella <luca-frequenz@llucax.com>

Author: llucax

tests/cookiecutter/scripts/test_dependabot-grpc-fixer.py

@@ -1,49 +1,20 @@
 """Tests for the dependabot_gprc_fixer package."""
 
-import importlib.util
 import json
 import re
 import runpy
 import shutil
 import sys
 from dataclasses import dataclass
 from pathlib import Path
-from typing import Protocol, cast
 
 import pytest
 
-# The script is not intended to be imported as a module, so we load it "dynamically"
-# here to test do some unit testing of its internal functions.
 FIXER_PATH = (
     Path(__file__).resolve().parents[3]
     / "cookiecutter/scripts/dependabot-grpc-fixer.py"
 )
-
-
-class FixerModule(Protocol):
-    """Typing contract for the loaded fixer script."""
-
-    PYPROJECT: Path
-
-    def main(self) -> None:
-        """Run the fixer script."""
-
-    def replace_range(self, text: str, name: str, version: str) -> tuple[str, int]:
-        """Update a dependency range."""
-
-
-def _load_fixer() -> FixerModule:
-    """Load the fixer script as a module for direct testing."""
-    spec = importlib.util.spec_from_file_location("fixer", FIXER_PATH)
-    if spec is None or spec.loader is None:
-        raise AssertionError(f"could not load {FIXER_PATH}")
-
-    module = importlib.util.module_from_spec(spec)
-    spec.loader.exec_module(module)
-    return cast(FixerModule, module)
-
-
-fixer = _load_fixer()
+PYPROJECT = Path("pyproject.toml")
 
 CASE_ROOT = Path(__file__).with_name("fixtures") / "dependabot-grpc-fixer"
 
@@ -107,15 +78,15 @@ def _prepare_workspace(
     input_dir = case.path / "input"
     input_pyproject = input_dir / "pyproject.toml"
     if input_pyproject.exists():
-        shutil.copyfile(input_pyproject, tmp_path / fixer.PYPROJECT.name)
+        shutil.copyfile(input_pyproject, tmp_path / PYPROJECT.name)
     monkeypatch.chdir(tmp_path)
     monkeypatch.setattr(sys, "argv", [str(FIXER_PATH)])
     input_metadata = input_dir / "dependabot-metadata.json"
     monkeypatch.setenv(
         "UPDATED_DEPENDENCIES_JSON",
         input_metadata.read_text(encoding="utf-8") if input_metadata.exists() else "",
     )
-    return tmp_path / fixer.PYPROJECT.name
+    return tmp_path / PYPROJECT.name
 
 
 @pytest.mark.parametrize(
@@ -131,10 +102,10 @@ def test_fixer_cases(
     workspace = _prepare_workspace(case, tmp_path, monkeypatch)
     if case.stderr_exact is not None or case.stderr_contains is not None:
         with pytest.raises(SystemExit) as excinfo:
-            fixer.main()
+            runpy.run_path(str(FIXER_PATH), run_name="__main__")
         assert excinfo.value.code == 1
     else:
-        fixer.main()
+        runpy.run_path(str(FIXER_PATH), run_name="__main__")
 
     captured = capsys.readouterr()
 
@@ -217,37 +188,6 @@ def test_fixer_runs_as_script_with_custom_pyproject_path(
     ) == case.expected_pyproject.read_text(encoding="utf-8")
 
 
-@pytest.mark.parametrize(
-    ("dependency", "version", "original", "expected"),
-    [
-        (
-            "grpcio",
-            "2.0.0",
-            '"grpcio >= 1.72.1, < 2", # Do not widen beyond 2!',
-            '"grpcio >= 2.0.0, < 3", # Do not widen beyond 3!',
-        ),
-        (
-            "protobuf",
-            "7.34.1",
-            '"protobuf >= 6.32.1, < 7", # Do not widen beyond 7!',
-            '"protobuf >= 7.34.1, < 9", # Do not widen beyond 9!',
-        ),
-    ],
-    ids=lambda case: case[0],
-)
-def test_replace_range_uses_dependency_specific_upper_bounds(
-    dependency: str,
-    version: str,
-    original: str,
-    expected: str,
-) -> None:
-    """Use the configured compatibility window for each runtime dependency."""
-    updated, count = fixer.replace_range(original, dependency, version)
-
-    assert count == 1
-    assert updated == expected
-
-
 # Integration: run the fixer against pyproject.toml files generated by the
 # cookiecutter template (as captured in tests_golden/). The fixer only applies
 # to API repositories, so we discover every `api*` golden case automatically.
@@ -384,7 +324,7 @@ def test_fixer_against_generated_api_pyproject(
     assert expected_protobuf_upper != protobuf_upper
     assert expected_grpcio_upper != grpcio_upper
 
-    workspace = tmp_path / fixer.PYPROJECT.name
+    workspace = tmp_path / PYPROJECT.name
     shutil.copyfile(golden_pyproject, workspace)
     monkeypatch.chdir(tmp_path)
     monkeypatch.setattr(sys, "argv", [str(FIXER_PATH)])
@@ -395,7 +335,7 @@ def test_fixer_against_generated_api_pyproject(
         ),
     )
 
-    fixer.main()
+    runpy.run_path(str(FIXER_PATH), run_name="__main__")
 
     captured = capsys.readouterr()
     assert (