diff --git a/libs/core/tests/unit_tests/load/test_serializable.py b/libs/core/tests/unit_tests/load/test_serializable.py
index 59bb6d54697..e782709fd41 100644
--- a/libs/core/tests/unit_tests/load/test_serializable.py
+++ b/libs/core/tests/unit_tests/load/test_serializable.py
@@ -1,6 +1,9 @@
+import json
+
+import pytest
 from pydantic import BaseModel, ConfigDict, Field
 
-from langchain_core.load import Serializable, dumpd, load
+from langchain_core.load import Serializable, dumpd, dumps, load
 from langchain_core.load.serializable import _is_field_useful
 from langchain_core.messages import AIMessage
 from langchain_core.outputs import ChatGeneration, Generation
@@ -276,3 +279,92 @@ def test_serialization_with_ignore_unserializable_fields() -> None:
             ]
         ]
     }
+
+
+# Tests for dumps() function
+def test_dumps_basic_serialization() -> None:
+    """Test basic string serialization with `dumps()`."""
+    foo = Foo(bar=42, baz="test")
+    json_str = dumps(foo)
+
+    # Should be valid JSON
+    parsed = json.loads(json_str)
+    assert parsed == {
+        "id": ["tests", "unit_tests", "load", "test_serializable", "Foo"],
+        "kwargs": {"bar": 42, "baz": "test"},
+        "lc": 1,
+        "type": "constructor",
+    }
+
+
+def test_dumps_pretty_formatting() -> None:
+    """Test pretty printing functionality."""
+    foo = Foo(bar=1, baz="hello")
+
+    # Test pretty=True with default indent
+    pretty_json = dumps(foo, pretty=True)
+    assert "  " in pretty_json
+
+    # Test custom indent (4-space)
+    custom_indent = dumps(foo, pretty=True, indent=4)
+    assert "    " in custom_indent
+
+    # Verify it's still valid JSON
+    parsed = json.loads(pretty_json)
+    assert parsed["kwargs"]["bar"] == 1
+
+
+def test_dumps_invalid_default_kwarg() -> None:
+    """Test that passing `'default'` as kwarg raises ValueError."""
+    foo = Foo(bar=1, baz="test")
+
+    with pytest.raises(ValueError, match="`default` should not be passed to dumps"):
+        dumps(foo, default=lambda x: x)
+
+
+def test_dumps_additional_json_kwargs() -> None:
+    """Test that additional JSON kwargs are passed through."""
+    foo = Foo(bar=1, baz="test")
+
+    compact_json = dumps(foo, separators=(",", ":"))
+    assert ", " not in compact_json  # Should be compact
+
+    # Test sort_keys
+    sorted_json = dumps(foo, sort_keys=True)
+    parsed = json.loads(sorted_json)
+    assert parsed == dumpd(foo)
+
+
+def test_dumps_non_serializable_object() -> None:
+    """Test `dumps()` behavior with non-serializable objects."""
+
+    class NonSerializable:
+        def __init__(self, value: int) -> None:
+            self.value = value
+
+    obj = NonSerializable(42)
+    json_str = dumps(obj)
+
+    # Should create a "not_implemented" representation
+    parsed = json.loads(json_str)
+    assert parsed["lc"] == 1
+    assert parsed["type"] == "not_implemented"
+    assert "NonSerializable" in parsed["repr"]
+
+
+def test_dumps_mixed_data_structure() -> None:
+    """Test `dumps()` with complex nested data structures."""
+    data = {
+        "serializable": Foo(bar=1, baz="test"),
+        "list": [1, 2, {"nested": "value"}],
+        "primitive": "string",
+    }
+
+    json_str = dumps(data)
+    parsed = json.loads(json_str)
+
+    # Serializable object should be properly serialized
+    assert parsed["serializable"]["type"] == "constructor"
+    # Primitives should remain unchanged
+    assert parsed["list"] == [1, 2, {"nested": "value"}]
+    assert parsed["primitive"] == "string"