google-vertexai[patch]: function calling integration test (#17209)

libs/partners/google-vertexai/tests/integration_tests/test_chat_models.py

@@ -1,4 +1,6 @@
 """Test ChatGoogleVertexAI chat model."""
+
+import json
 from typing import Optional, cast
 
 import pytest
@@ -9,6 +11,7 @@ from langchain_core.messages import (
     SystemMessage,
 )
 from langchain_core.outputs import ChatGeneration, LLMResult
+from langchain_core.pydantic_v1 import BaseModel
 
 from langchain_google_vertexai.chat_models import ChatVertexAI
 
@@ -220,3 +223,26 @@ def test_chat_vertexai_system_message(model_name: Optional[str]) -> None:
     response = model([system_message, message1, message2, message3])
     assert isinstance(response, AIMessage)
     assert isinstance(response.content, str)
+
+
+def test_chat_vertexai_gemini_function_calling() -> None:
+    class MyModel(BaseModel):
+        name: str
+        age: int
+
+    model = ChatVertexAI(model_name="gemini-pro").bind(functions=[MyModel])
+    message = HumanMessage(content="My name is Erick and I am 27 years old")
+    response = model.invoke([message])
+    assert isinstance(response, AIMessage)
+    assert isinstance(response.content, str)
+    assert response.content == ""
+    function_call = response.additional_kwargs.get("function_call")
+    assert function_call
+    assert function_call["name"] == "MyModel"
+    arguments_str = function_call.get("arguments")
+    assert arguments_str
+    arguments = json.loads(arguments_str)
+    assert arguments == {
+        "name": "Erick",
+        "age": 27.0,
+    }