infra: ChatOpenAI unit tests for invoke() and ainvoke() (#18792)

**Description:** Replacing the deprecated predict() and apredict()
methods in the unit tests
**Issue:** Not applicable
**Dependencies:** None
**Lint and test**: `make format`, `make lint` and `make test` have been
run

libs/partners/openai/tests/unit_tests/chat_models/test_base.py

@@ -1,7 +1,7 @@
 """Test OpenAI Chat API wrapper."""
 import json
 from typing import Any
-from unittest.mock import MagicMock, patch
+from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
 from langchain_core.messages import (
@@ -78,7 +78,7 @@ def mock_completion() -> dict:
     }
 
 
-def test_openai_predict(mock_completion: dict) -> None:
+def test_openai_invoke(mock_completion: dict) -> None:
     llm = ChatOpenAI()
     mock_client = MagicMock()
     completed = False
@@ -94,17 +94,17 @@ def test_openai_predict(mock_completion: dict) -> None:
         "client",
         mock_client,
     ):
-        res = llm.predict("bar")
-        assert res == "Bar Baz"
+        res = llm.invoke("bar")
+        assert res.content == "Bar Baz"
     assert completed
 
 
-async def test_openai_apredict(mock_completion: dict) -> None:
+async def test_openai_ainvoke(mock_completion: dict) -> None:
     llm = ChatOpenAI()
-    mock_client = MagicMock()
+    mock_client = AsyncMock()
     completed = False
 
-    def mock_create(*args: Any, **kwargs: Any) -> Any:
+    async def mock_create(*args: Any, **kwargs: Any) -> Any:
         nonlocal completed
         completed = True
         return mock_completion
@@ -112,11 +112,11 @@ async def test_openai_apredict(mock_completion: dict) -> None:
     mock_client.create = mock_create
     with patch.object(
         llm,
-        "client",
+        "async_client",
         mock_client,
     ):
-        res = llm.predict("bar")
-        assert res == "Bar Baz"
+        res = await llm.ainvoke("bar")
+        assert res.content == "Bar Baz"
     assert completed