chore(core): add mypy pydantic plugin (#32604)

This helps to remove a bunch of mypy false positives.

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

@@ -810,7 +810,7 @@ def test_parse_with_different_pydantic_2_v1() -> None:
 
     # Can't get pydantic to work here due to the odd typing of tryig to support
     # both v1 and v2 in the same codebase.
-    parser = PydanticToolsParser(tools=[Forecast])  # type: ignore[list-item]
+    parser = PydanticToolsParser(tools=[Forecast])
     message = AIMessage(
         content="",
         tool_calls=[

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

@@ -13,7 +13,7 @@ from langchain_core.language_models import ParrotFakeChatModel
 from langchain_core.output_parsers import PydanticOutputParser
 from langchain_core.output_parsers.json import JsonOutputParser
 from langchain_core.prompts.prompt import PromptTemplate
-from langchain_core.utils.pydantic import TBaseModel
+from langchain_core.utils.pydantic import PydanticBaseModel, TBaseModel
 
 
 class ForecastV2(pydantic.BaseModel):
@@ -43,7 +43,7 @@ def test_pydantic_parser_chaining(
 
     model = ParrotFakeChatModel()
 
-    parser = PydanticOutputParser(pydantic_object=pydantic_object)  # type: ignore[type-var]
+    parser = PydanticOutputParser[PydanticBaseModel](pydantic_object=pydantic_object)
     chain = prompt | model | parser
 
     res = chain.invoke({})
@@ -66,7 +66,9 @@ def test_pydantic_parser_validation(pydantic_object: TBaseModel) -> None:
 
     model = ParrotFakeChatModel()
 
-    parser = PydanticOutputParser(pydantic_object=pydantic_object)  # type: ignore[arg-type,var-annotated]
+    parser: PydanticOutputParser[PydanticBaseModel] = PydanticOutputParser(
+        pydantic_object=pydantic_object
+    )
     chain = bad_prompt | model | parser
     with pytest.raises(OutputParserException):
         chain.invoke({})
@@ -88,7 +90,7 @@ def test_json_parser_chaining(
 
     model = ParrotFakeChatModel()
 
-    parser = JsonOutputParser(pydantic_object=pydantic_object)  # type: ignore[arg-type]
+    parser = JsonOutputParser(pydantic_object=pydantic_object)
     chain = prompt | model | parser
 
     res = chain.invoke({})
@@ -171,7 +173,7 @@ def test_pydantic_output_parser_type_inference() -> None:
 
     # Ignoring mypy error that appears in python 3.8, but not 3.11.
     # This seems to be functionally correct, so we'll ignore the error.
-    pydantic_parser = PydanticOutputParser(pydantic_object=SampleModel)
+    pydantic_parser = PydanticOutputParser[SampleModel](pydantic_object=SampleModel)
     schema = pydantic_parser.get_output_schema().model_json_schema()
 
     assert schema == {
@@ -202,5 +204,5 @@ def test_format_instructions_preserves_language() -> None:
             )
         )
 
-    parser = PydanticOutputParser(pydantic_object=Foo)
+    parser = PydanticOutputParser[Foo](pydantic_object=Foo)
     assert description in parser.get_format_instructions()

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

@@ -348,7 +348,7 @@ def test_prompt_invalid_template_format() -> None:
         PromptTemplate(
             input_variables=input_variables,
             template=template,
-            template_format="bar",  # type: ignore[arg-type]
+            template_format="bar",
         )
 
 

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

@@ -73,7 +73,7 @@ class MyOtherRunnable(RunnableSerializable[str, str]):
 
 def test_doubly_set_configurable() -> None:
     """Test that setting a configurable field with a default value works."""
-    runnable = MyRunnable(my_property="a")  # type: ignore[call-arg]
+    runnable = MyRunnable(my_property="a")
     configurable_runnable = runnable.configurable_fields(
         my_property=ConfigurableField(
             id="my_property",
@@ -86,7 +86,7 @@ def test_doubly_set_configurable() -> None:
 
 
 def test_alias_set_configurable() -> None:
-    runnable = MyRunnable(my_property="a")  # type: ignore[call-arg]
+    runnable = MyRunnable(my_property="a")
     configurable_runnable = runnable.configurable_fields(
         my_property=ConfigurableField(
             id="my_property_alias",
@@ -104,7 +104,7 @@ def test_alias_set_configurable() -> None:
 
 
 def test_field_alias_set_configurable() -> None:
-    runnable = MyRunnable(my_property_alias="a")
+    runnable = MyRunnable(my_property_alias="a")  # type: ignore[call-arg]
     configurable_runnable = runnable.configurable_fields(
         my_property=ConfigurableField(
             id="my_property",
@@ -122,7 +122,7 @@ def test_field_alias_set_configurable() -> None:
 
 
 def test_config_passthrough() -> None:
-    runnable = MyRunnable(my_property="a")  # type: ignore[call-arg]
+    runnable = MyRunnable(my_property="a")
     configurable_runnable = runnable.configurable_fields(
         my_property=ConfigurableField(
             id="my_property",
@@ -158,7 +158,7 @@ def test_config_passthrough() -> None:
 
 
 def test_config_passthrough_nested() -> None:
-    runnable = MyRunnable(my_property="a")  # type: ignore[call-arg]
+    runnable = MyRunnable(my_property="a")
     configurable_runnable = runnable.configurable_fields(
         my_property=ConfigurableField(
             id="my_property",

libs/core/tests/unit_tests/utils/test_utils.py

@@ -347,7 +347,7 @@ def test_using_secret_from_env_as_default_factory(
         secret: SecretStr = Field(default_factory=secret_from_env("TEST_KEY"))
 
     # Pass the secret as a parameter
-    foo = Foo(secret="super_secret")  # type: ignore[arg-type]
+    foo = Foo(secret="super_secret")
     assert foo.secret.get_secret_value() == "super_secret"
 
     # Set the environment variable