Add TypeAdapter for EvaluatorContext

pydantic_evals/pydantic_evals/evaluators/context.py

@@ -9,6 +9,7 @@
 from dataclasses import dataclass, field
 from typing import Any, Generic
 
+from pydantic import TypeAdapter
 from typing_extensions import TypeVar
 
 from ..otel._errors import SpanTreeRecordingError
@@ -100,3 +101,7 @@ def span_tree(self) -> SpanTree:
             # In this case, there was a reason we couldn't record the SpanTree. We raise that now
             raise self._span_tree
         return self._span_tree
+
+
+EVALUATOR_CONTEXT_ADAPTER = TypeAdapter(EvaluatorContext)
+"""This adapter can be used to serialize and deserialize `EvaluatorContext` objects to and from JSON."""

pydantic_evals/pydantic_evals/otel/_errors.py

@@ -1,7 +1,34 @@
+from typing import Any
+
+from pydantic_core import core_schema
+
+
 class SpanTreeRecordingError(Exception):
     """An exception that is used to provide the reason why a SpanTree was not recorded by `context_subtree`.
 
     This will either be due to missing dependencies or because a tracer provider had not been set.
     """
 
-    pass
+    message: str
+
+    def __init__(self, message: str):
+        self.message = message
+        super().__init__(message)
+
+    @classmethod
+    def __get_pydantic_core_schema__(cls, _: Any, __: Any) -> core_schema.CoreSchema:
+        """Pydantic core schema to allow `SpanTreeRecordingError` to be (de)serialized."""
+        schema = core_schema.typed_dict_schema(
+            {
+                'message': core_schema.typed_dict_field(core_schema.str_schema()),
+                'kind': core_schema.typed_dict_field(core_schema.literal_schema(['span-tree-recording-error'])),
+            }
+        )
+        return core_schema.no_info_after_validator_function(
+            lambda dct: SpanTreeRecordingError(dct['message']),
+            schema,
+            serialization=core_schema.plain_serializer_function_ser_schema(
+                lambda x: {'message': x.message, 'kind': 'span-tree-recording-error'},
+                return_schema=schema,
+            ),
+        )