diff --git a/libs/core/tests/unit_tests/messages/test_utils.py b/libs/core/tests/unit_tests/messages/test_utils.py
index 142272292f609..3f25e02fb2381 100644
--- a/libs/core/tests/unit_tests/messages/test_utils.py
+++ b/libs/core/tests/unit_tests/messages/test_utils.py
@@ -1,3 +1,4 @@
+import json
 from typing import Dict, List, Type
 
 import pytest
@@ -12,6 +13,7 @@
     ToolMessage,
 )
 from langchain_core.messages.utils import (
+    convert_to_messages,
     filter_messages,
     merge_message_runs,
     trim_messages,
@@ -357,3 +359,176 @@ def dummy_token_counter(messages: List[BaseMessage]) -> int:
 class FakeTokenCountingModel(FakeChatModel):
     def get_num_tokens_from_messages(self, messages: List[BaseMessage]) -> int:
         return dummy_token_counter(messages)
+
+
+def test_convert_to_messages() -> None:
+    message_like: List = [
+        # BaseMessage
+        SystemMessage("1"),
+        HumanMessage([{"type": "image_url", "image_url": {"url": "2.1"}}], name="2.2"),
+        AIMessage(
+            [
+                {"type": "text", "text": "3.1"},
+                {
+                    "type": "tool_use",
+                    "id": "3.2",
+                    "name": "3.3",
+                    "input": {"3.4": "3.5"},
+                },
+            ]
+        ),
+        AIMessage(
+            [
+                {"type": "text", "text": "4.1"},
+                {
+                    "type": "tool_use",
+                    "id": "4.2",
+                    "name": "4.3",
+                    "input": {"4.4": "4.5"},
+                },
+            ],
+            tool_calls=[
+                {
+                    "name": "4.3",
+                    "args": {"4.4": "4.5"},
+                    "id": "4.2",
+                    "type": "tool_call",
+                }
+            ],
+        ),
+        ToolMessage("5.1", tool_call_id="5.2", name="5.3"),
+        # OpenAI dict
+        {"role": "system", "content": "6"},
+        {
+            "role": "user",
+            "content": [{"type": "image_url", "image_url": {"url": "7.1"}}],
+            "name": "7.2",
+        },
+        {
+            "role": "assistant",
+            "content": [{"type": "text", "text": "8.1"}],
+            "tool_calls": [
+                {
+                    "type": "function",
+                    "function": {
+                        "arguments": json.dumps({"8.2": "8.3"}),
+                        "name": "8.4",
+                    },
+                    "id": "8.5",
+                }
+            ],
+            "name": "8.6",
+        },
+        {"role": "tool", "content": "10.1", "tool_call_id": "10.2"},
+        # Tuple/List
+        ("system", "11.1"),
+        ("human", [{"type": "image_url", "image_url": {"url": "12.1"}}]),
+        (
+            "ai",
+            [
+                {"type": "text", "text": "13.1"},
+                {
+                    "type": "tool_use",
+                    "id": "13.2",
+                    "name": "13.3",
+                    "input": {"13.4": "13.5"},
+                },
+            ],
+        ),
+        # String
+        "14.1",
+        # LangChain dict
+        {
+            "role": "ai",
+            "content": [{"type": "text", "text": "15.1"}],
+            "tool_calls": [{"args": {"15.2": "15.3"}, "name": "15.4", "id": "15.5"}],
+            "name": "15.6",
+        },
+    ]
+    expected = [
+        SystemMessage(content="1"),
+        HumanMessage(
+            content=[{"type": "image_url", "image_url": {"url": "2.1"}}], name="2.2"
+        ),
+        AIMessage(
+            content=[
+                {"type": "text", "text": "3.1"},
+                {
+                    "type": "tool_use",
+                    "id": "3.2",
+                    "name": "3.3",
+                    "input": {"3.4": "3.5"},
+                },
+            ]
+        ),
+        AIMessage(
+            content=[
+                {"type": "text", "text": "4.1"},
+                {
+                    "type": "tool_use",
+                    "id": "4.2",
+                    "name": "4.3",
+                    "input": {"4.4": "4.5"},
+                },
+            ],
+            tool_calls=[
+                {
+                    "name": "4.3",
+                    "args": {"4.4": "4.5"},
+                    "id": "4.2",
+                    "type": "tool_call",
+                }
+            ],
+        ),
+        ToolMessage(content="5.1", name="5.3", tool_call_id="5.2"),
+        SystemMessage(content="6"),
+        HumanMessage(
+            content=[{"type": "image_url", "image_url": {"url": "7.1"}}], name="7.2"
+        ),
+        AIMessage(
+            content=[{"type": "text", "text": "8.1"}],
+            name="8.6",
+            tool_calls=[
+                {
+                    "name": "8.4",
+                    "args": {"8.2": "8.3"},
+                    "id": "8.5",
+                    "type": "tool_call",
+                }
+            ],
+        ),
+        ToolMessage(content="10.1", tool_call_id="10.2"),
+        SystemMessage(content="11.1"),
+        HumanMessage(content=[{"type": "image_url", "image_url": {"url": "12.1"}}]),
+        AIMessage(
+            content=[
+                {"type": "text", "text": "13.1"},
+                {
+                    "type": "tool_use",
+                    "id": "13.2",
+                    "name": "13.3",
+                    "input": {"13.4": "13.5"},
+                },
+            ]
+        ),
+        HumanMessage(content="14.1"),
+        AIMessage(
+            content=[{"type": "text", "text": "15.1"}],
+            name="15.6",
+            tool_calls=[
+                {
+                    "name": "15.4",
+                    "args": {"15.2": "15.3"},
+                    "id": "15.5",
+                    "type": "tool_call",
+                }
+            ],
+        ),
+    ]
+    actual = convert_to_messages(message_like)
+    assert expected == actual
+
+
+@pytest.mark.xfail(reason="AI message does not support refusal key yet.")
+def test_convert_to_messages_openai_refusal() -> None:
+    convert_to_messages([{"role": "assistant", "refusal": "9.1"}])