fix: support hexadecimal OpenFeature numeric variants (#980)

* fix: support hexadecimal OpenFeature numeric variants

* fix: preserve numeric variants and parse large hex integers directly

Author: marandaneto

.sampo/changesets/cranky-duchess-ilmatar.md

@@ -0,0 +1,5 @@
+---
+pypi/openfeature-provider-posthog: patch
+---
+
+Support hexadecimal numeric variants in the OpenFeature provider.

openfeature-provider/openfeature/contrib/provider/posthog/provider.py

@@ -8,6 +8,7 @@
 from __future__ import annotations
 
 import logging
+import re
 from typing import Any, Callable, Mapping, Optional, Sequence, TypeVar, Union
 
 from openfeature.evaluation_context import EvaluationContext
@@ -53,7 +54,9 @@ class PostHogProvider(AbstractProvider):
     Flag-type mapping (all via ``get_feature_flag_result``):
         * boolean -> ``enabled``
         * string  -> the multivariate ``variant`` key
-        * int/float -> the ``variant`` parsed to a number
+        * int/float -> the ``variant`` parsed to a number, including unsigned
+          hexadecimal integers such as ``0x10`` (returned as int or float,
+          respectively)
         * object  -> the flag's JSON ``payload``
 
     Args:
@@ -202,7 +205,7 @@ def _resolve_number(
         flag_key: str,
         default_value: _N,
         evaluation_context: Optional[EvaluationContext],
-        ctor: Callable[[str], _N],
+        ctor: Callable[[Union[str, int]], _N],
     ) -> FlagResolutionDetails[_N]:
         result = self._resolve(flag_key, evaluation_context)
         if result.variant is None:
@@ -213,8 +216,13 @@ def _resolve_number(
                 f"Flag '{flag_key}' has no variant to parse as {ctor.__name__}."
             )
         try:
-            value = ctor(result.variant)
-        except (TypeError, ValueError) as exc:
+            variant: Union[str, int] = result.variant
+            if isinstance(variant, str) and re.fullmatch(
+                r"0[xX][0-9a-fA-F]+", variant.strip()
+            ):
+                variant = int(variant, 16)
+            value = ctor(variant)
+        except (TypeError, ValueError, OverflowError) as exc:
             raise TypeMismatchError(
                 f"Flag '{flag_key}' variant '{result.variant}' is not a valid "
                 f"{ctor.__name__}."

openfeature-provider/tests/test_provider_unit.py

@@ -73,6 +73,10 @@ def test_string_on_boolean_flag_is_type_mismatch(fake_client):
         ("resolve_integer_details", "3", 3),
         ("resolve_float_details", "3.5", 3.5),
         ("resolve_float_details", "3", 3.0),
+        ("resolve_integer_details", 42, 42),
+        ("resolve_integer_details", 3.5, 3),
+        ("resolve_float_details", 42, 42.0),
+        ("resolve_float_details", 3.5, 3.5),
     ],
 )
 def test_number_variant_parse(fake_client, resolver, variant, expected):
@@ -100,6 +104,63 @@ def test_number_variant_parse_failure(fake_client, resolver, variant):
         getattr(_provider(fake_client), resolver)("n", 0, EvaluationContext("u"))
 
 
+@pytest.mark.parametrize(
+    "resolver", ["resolve_integer_details", "resolve_float_details"]
+)
+@pytest.mark.parametrize(
+    ("variant", "expected"),
+    [("0x10", 16), ("0Xff", 255), (" 0xA0 ", 160), ("0x0", 0), ("042", 42)],
+)
+def test_hex_number_variant(fake_client, resolver, variant, expected):
+    fake_client.get_feature_flag_result.return_value = make_result(variant=variant)
+    details = getattr(_provider(fake_client), resolver)("n", 0, EvaluationContext("u"))
+    assert details.value == expected
+    assert type(details.value) is (
+        int if resolver == "resolve_integer_details" else float
+    )
+    assert details.variant == variant
+
+
+@pytest.mark.parametrize(
+    "resolver", ["resolve_integer_details", "resolve_float_details"]
+)
+@pytest.mark.parametrize(
+    "variant", ["0x", "0xgg", "0x1.5", "0x_10", "0x1_0", "-0x10", "+0x10"]
+)
+def test_invalid_hex_number_variant(fake_client, resolver, variant):
+    fake_client.get_feature_flag_result.return_value = make_result(variant=variant)
+    with pytest.raises(TypeMismatchError):
+        getattr(_provider(fake_client), resolver)("n", 0, EvaluationContext("u"))
+
+
+def test_hex_integer_beyond_decimal_string_limit(fake_client):
+    variant = "0x" + "f" * 4000
+    fake_client.get_feature_flag_result.return_value = make_result(variant=variant)
+    details = _provider(fake_client).resolve_integer_details(
+        "n", 0, EvaluationContext("u")
+    )
+    assert details.value == (1 << 16000) - 1
+    assert details.variant == variant
+
+
+def test_large_representable_hex_float(fake_client):
+    variant = "0x" + "f" * 255
+    fake_client.get_feature_flag_result.return_value = make_result(variant=variant)
+    details = _provider(fake_client).resolve_float_details(
+        "n", 0.0, EvaluationContext("u")
+    )
+    assert details.value == float(int(variant, 16))
+    assert isinstance(details.value, float)
+
+
+def test_hex_float_overflow_is_type_mismatch(fake_client):
+    fake_client.get_feature_flag_result.return_value = make_result(
+        variant="0x" + "f" * 4000
+    )
+    with pytest.raises(TypeMismatchError):
+        _provider(fake_client).resolve_float_details("n", 0.0, EvaluationContext("u"))
+
+
 def test_object_payload(fake_client):
     fake_client.get_feature_flag_result.return_value = make_result(
         enabled=True, variant="v1", payload={"color": "blue"}