fix: use 'is True' for _is_internal_hook_provider check to prevent Mock false positives on Python <3.12

On Python <3.12, isinstance() against @runtime_checkable Protocols matches
Mock objects (structural subtyping checks were tightened in 3.12). The
existing getattr guard used a truthiness check, but Mock auto-creates
attributes as truthy MagicMock objects, so the guard was ineffective.
Switching to 'is True' identity check ensures only objects that explicitly
set _is_internal_hook_provider = True (a literal bool) pass the guard.

Also flattens nested conditional in ComparisonStrategy.determine_final_result.

Signed-off-by: Jonathan Norris <jonathan.norris@dynatrace.com>

Author: jonathannorris

openfeature/client.py

@@ -475,7 +475,7 @@ def _as_internal_hook_provider(
         self, provider: FeatureProvider
     ) -> InternalHookProvider | None:
         """Return the provider as InternalHookProvider if it opts in, else None."""
-        if getattr(provider, "_is_internal_hook_provider", False) and isinstance(
+        if getattr(provider, "_is_internal_hook_provider", False) is True and isinstance(
             provider, InternalHookProvider
         ):
             return provider

openfeature/provider/_registry.py

@@ -127,7 +127,7 @@ def get_provider_status(self, provider: FeatureProvider) -> ProviderStatus:
         # We check _is_internal_hook_provider (a concrete class attribute) in
         # addition to isinstance, because runtime_checkable Protocols match any
         # object that has the right method names — including Mock objects.
-        if getattr(provider, "_is_internal_hook_provider", False) and isinstance(
+        if getattr(provider, "_is_internal_hook_provider", False) is True and isinstance(
             provider, InternalHookProvider
         ):
             return provider.get_status()

openfeature/provider/multi_provider.py

@@ -305,26 +305,26 @@ def determine_final_result(
         # The first provider's result is the "final resolution" (used on agreement).
         # The fallback provider's result is used on mismatch (per JS SDK reference).
         final_evaluation = evaluations[0]
-        fallback_evaluation = self._select_fallback_evaluation(evaluations)
         reference_value = final_evaluation.result.value
-        has_mismatch = any(
+        if not any(
             evaluation.result.value != reference_value for evaluation in evaluations
-        )
-        if has_mismatch:
-            if self.on_mismatch is not None:
-                mismatch_results = {
-                    evaluation.provider_name: evaluation.result
-                    for evaluation in evaluations
-                }
-                try:
-                    self.on_mismatch(flag_key, mismatch_results)
-                except Exception:
-                    logger.exception(
-                        "Comparison strategy mismatch callback failed for flag '%s'",
-                        flag_key,
-                    )
-            return fallback_evaluation.result
-        return final_evaluation.result
+        ):
+            return final_evaluation.result
+
+        fallback_evaluation = self._select_fallback_evaluation(evaluations)
+        if self.on_mismatch is not None:
+            mismatch_results = {
+                evaluation.provider_name: evaluation.result
+                for evaluation in evaluations
+            }
+            try:
+                self.on_mismatch(flag_key, mismatch_results)
+            except Exception:
+                logger.exception(
+                    "Comparison strategy mismatch callback failed for flag '%s'",
+                    flag_key,
+                )
+        return fallback_evaluation.result
 
     def _select_fallback_evaluation(
         self, evaluations: list[_ProviderEvaluation[FlagValueType]]