standard-tests: add test for structured output (#23631)

- add test for structured output
- fix bug with structured output for Azure
- better testing on Groq (break out Mixtral + Llama3 and add xfails
where needed)

libs/standard-tests/langchain_standard_tests/integration_tests/chat_models.py

@@ -12,6 +12,7 @@ from langchain_core.messages import (
     HumanMessage,
     ToolMessage,
 )
+from langchain_core.pydantic_v1 import BaseModel, Field
 from langchain_core.tools import tool
 
 from langchain_standard_tests.unit_tests.chat_models import (
@@ -139,6 +140,20 @@ class ChatModelIntegrationTests(ChatModelTests):
         assert isinstance(full, AIMessage)
         _validate_tool_call_message(full)
 
+    def test_structured_output(self, model: BaseChatModel) -> None:
+        if not self.has_tool_calling:
+            pytest.skip("Test requires tool calling.")
+
+        class Joke(BaseModel):
+            """Joke to tell user."""
+
+            setup: str = Field(description="question to set up a joke")
+            punchline: str = Field(description="answer to resolve the joke")
+
+        chat = model.with_structured_output(Joke)
+        result = chat.invoke("Tell me a joke about cats.")
+        assert isinstance(result, Joke)
+
     def test_tool_message_histories_string_content(
         self,
         model: BaseChatModel,