expose KNOWN_ARCHITECTURES as public API (#56)

- Add KNOWN_ARCHITECTURES frozenset to _py_info.py and export it from
the package's public API
  - Expand normalize_isa() to also normalize i386 and i586 → x86
  - Update test to reference the new constant instead of a hardcoded set

Co-authored-by: Rahul Devikar <radevika@microsoft.com>

Author: rahuldevikar

src/python_discovery/__init__.py

@@ -6,13 +6,14 @@
 
 from ._cache import ContentStore, DiskCache, PyInfoCache
 from ._discovery import get_interpreter
-from ._py_info import PythonInfo
+from ._py_info import KNOWN_ARCHITECTURES, PythonInfo
 from ._py_spec import PythonSpec
 from ._specifier import SimpleSpecifier, SimpleSpecifierSet, SimpleVersion
 
 __version__ = version("python-discovery")
 
 __all__ = [
+    "KNOWN_ARCHITECTURES",
     "ContentStore",
     "DiskCache",
     "PyInfoCache",

src/python_discovery/_py_info.py

@@ -768,9 +768,23 @@ def _possible_base(self) -> Generator[str, None, None]:
                     yield upper
 
 
+KNOWN_ARCHITECTURES: frozenset[str] = frozenset({
+    "arm64",
+    "i686",
+    "loongarch64",
+    "ppc64",
+    "ppc64le",
+    "riscv64",
+    "s390x",
+    "x86",
+    "x86_64",
+})
+"""Known CPU architecture (ISA) values after normalization."""
+
+
 def normalize_isa(isa: str) -> str:
     low = isa.lower()
-    return {"amd64": "x86_64", "aarch64": "arm64"}.get(low, low)
+    return {"amd64": "x86_64", "aarch64": "arm64", "i386": "x86", "i586": "x86"}.get(low, low)
 
 
 def _main() -> None:  # pragma: no cover

tests/py_info/test_py_info.py

@@ -14,7 +14,7 @@
 import pytest
 from setuptools.dist import Distribution
 
-from python_discovery import DiskCache, PythonInfo, PythonSpec
+from python_discovery import KNOWN_ARCHITECTURES, DiskCache, PythonInfo, PythonSpec
 from python_discovery import _cached_py_info as cached_py_info
 from python_discovery._py_info import VersionInfo
 
@@ -338,8 +338,7 @@ def test_py_info_machine_property() -> None:
     assert machine is not None
     assert isinstance(machine, str)
     assert len(machine) > 0
-    known_isas = {"arm64", "i686", "loongarch64", "ppc64", "ppc64le", "riscv64", "s390x", "x86", "x86_64"}
-    assert machine in known_isas, f"unexpected machine value: {machine}"
+    assert machine in KNOWN_ARCHITECTURES, f"unexpected machine value: {machine}"
 
 
 def test_py_info_machine_in_spec() -> None: