chore: Extract allowed values (#4342)

This pull request focuses on improving maintainability by extracting and
explicitly defining allowed values for settings classes. The main change
ensures that allowed values are clearly listed and type-annotated, which
will help with code clarity and future maintenance.

Settings class allowed values extraction:

* Added the `_allowed_values` attribute to settings classes in both
implementation and stub files, making allowed values explicit and
type-annotated (`src/ansys/fluent/core/codegen/settingsgen.py`).
* Documented the extraction of allowed values in the changelog
(`doc/changelog.d/4342.maintenance.md`).

---------

Co-authored-by: pyansys-ci-bot <[email protected]>

Author: hpohekar

doc/changelog.d/4342.maintenance.md

@@ -0,0 +1 @@
+Extract allowed values

src/ansys/fluent/core/codegen/settingsgen.py

@@ -316,6 +316,9 @@ def _write_data(cls_name: str, python_name: str, data: dict, f: IO, f_stub: IO |
         s_stub.write(
             f"    {to_constant_name(allowed_value)}: Final[str] = {allowed_value!r}\n"
         )
+    if data["allowed_values"]:
+        s.write(f"    _allowed_values = {data['allowed_values']!r}\n")
+        s_stub.write("    _allowed_values: list[str]\n")
     s.write("\n")
     s_stub.write("\n")
     for name, (python_name, data, hash_, should_write_stub) in classes_to_write.items():

tests/test_codegen.py

@@ -56,6 +56,23 @@ def test_allapigen_files(new_solver_session):
     importlib.import_module(f"ansys.fluent.core.generated.solver.settings_{version}")
 
 
+@pytest.mark.fluent_version(">=26.1")
+@pytest.mark.codegen_required
+def test_settings_allowed_values(new_solver_session):
+    version = get_version_for_file_name(session=new_solver_session)
+    module = importlib.import_module(
+        f"ansys.fluent.core.generated.solver.settings_{version}"
+    )
+
+    file_type_1 = getattr(module, "file_type_1")
+    assert set(file_type_1._allowed_values) == set(
+        ["case", "case-data", "data", "mesh"]
+    )
+
+    unit = getattr(module, "unit")
+    assert set(unit._allowed_values) == set(["m", "cm", "mm", "in", "ft"])
+
+
 def test_codegen_with_no_static_info(monkeypatch):
     codegen_outdir = Path(tempfile.mkdtemp())
     monkeypatch.setattr(pyfluent.config, "codegen_outdir", codegen_outdir)