(test) add langchain ChatLiteLLM testing

litellm/tests/test_langchain_ChatLiteLLM.py

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+import os
+import sys, os
+import traceback
+from dotenv import load_dotenv
+
+load_dotenv()
+import os, io
+
+sys.path.insert(
+    0, os.path.abspath("../..")
+)  # Adds the parent directory to the system path
+import pytest
+import litellm
+from litellm import embedding, completion, text_completion, completion_cost
+
+from langchain.chat_models import ChatLiteLLM
+from langchain.prompts.chat import (
+    ChatPromptTemplate,
+    SystemMessagePromptTemplate,
+    AIMessagePromptTemplate,
+    HumanMessagePromptTemplate,
+)
+from langchain.schema import AIMessage, HumanMessage, SystemMessage
+
+def test_chat_gpt():
+    try:
+        chat = ChatLiteLLM(model="gpt-3.5-turbo", max_tokens=10)
+        messages = [
+            HumanMessage(
+                content="what model are you"
+            )
+        ]
+        resp = chat(messages)
+
+        print(resp)
+    except Exception as e:
+        pytest.fail(f"Error occurred: {e}")
+
+test_chat_gpt()
+
+
+def test_claude():
+    try:
+        chat = ChatLiteLLM(model="claude-2", max_tokens=10)
+        messages = [
+            HumanMessage(
+                content="what model are you"
+            )
+        ]
+        resp = chat(messages)
+
+        print(resp)
+    except Exception as e:
+        pytest.fail(f"Error occurred: {e}")
+
+test_claude()
+
+def test_palm():
+    try:
+        chat = ChatLiteLLM(model="palm/chat-bison", max_tokens=10)
+        messages = [
+            HumanMessage(
+                content="what model are you"
+            )
+        ]
+        resp = chat(messages)
+
+        print(resp)
+    except Exception as e:
+        pytest.fail(f"Error occurred: {e}")
+
+test_palm()
+