core: Removing unnecessary pydantic core schema rebuilds (#30848)

We only need to rebuild model schemas if type annotation information
isn't available during declaration - that shouldn't be the case for
these types corrected here.

Need to do more thorough testing to make sure these structures have
complete schemas, but hopefully this boosts startup / import time.

libs/core/tests/unit_tests/language_models/chat_models/test_rate_limiting.py

@@ -227,9 +227,6 @@ class SerializableModel(GenericFakeChatModel):
         return True
 
 
-SerializableModel.model_rebuild()
-
-
 def test_serialization_with_rate_limiter() -> None:
     """Test model serialization with rate limiter."""
     from langchain_core.load import dumps

libs/core/tests/unit_tests/output_parsers/test_base_parsers.py

@@ -45,8 +45,6 @@ def test_base_generation_parser() -> None:
             assert isinstance(content, str)
             return content.swapcase()
 
-    StrInvertCase.model_rebuild()
-
     model = GenericFakeChatModel(messages=iter([AIMessage(content="hEllo")]))
     chain = model | StrInvertCase()
     assert chain.invoke("") == "HeLLO"

libs/core/tests/unit_tests/prompts/test_structured.py

@@ -35,9 +35,6 @@ class FakeStructuredChatModel(FakeListChatModel):
         return "fake-messages-list-chat-model"
 
 
-FakeStructuredChatModel.model_rebuild()
-
-
 def test_structured_prompt_pydantic() -> None:
     class OutputSchema(BaseModel):
         name: str

libs/core/tests/unit_tests/runnables/test_runnable_events_v1.py

@@ -1188,9 +1188,6 @@ class HardCodedRetriever(BaseRetriever):
         return self.documents
 
 
-HardCodedRetriever.model_rebuild()
-
-
 async def test_event_stream_with_retriever() -> None:
     """Test the event stream with a retriever."""
     retriever = HardCodedRetriever(

libs/core/tests/unit_tests/test_pydantic_imports.py

@@ -0,0 +1,20 @@
+import importlib
+from pathlib import Path
+
+from pydantic import BaseModel
+
+
+def test_all_models_built() -> None:
+    for path in Path("../core/langchain_core/").glob("*"):
+        module_name = path.stem
+        if not module_name.startswith(".") and path.suffix != ".typed":
+            module = importlib.import_module("langchain_core." + module_name)
+            all_ = getattr(module, "__all__", [])
+            for attr_name in all_:
+                attr = getattr(module, attr_name)
+                try:
+                    if issubclass(attr, BaseModel):
+                        assert attr.__pydantic_complete__ is True
+                except TypeError:
+                    # This is expected for non-class attributes
+                    pass

libs/core/tests/unit_tests/test_tools.py

@@ -1091,9 +1091,6 @@ class FooBase(BaseTool):
         return assert_bar(bar, bar_config)
 
 
-FooBase.model_rebuild()
-
-
 class AFooBase(FooBase):
     async def _arun(self, bar: Any, bar_config: RunnableConfig, **kwargs: Any) -> Any:
         return assert_bar(bar, bar_config)