core[patch]: utils for adding/subtracting usage metadata (#27203)

libs/core/tests/unit_tests/utils/test_usage.py

@@ -0,0 +1,38 @@
+import pytest
+
+from langchain_core.utils.usage import _dict_int_op
+
+
+def test_dict_int_op_add() -> None:
+    left = {"a": 1, "b": 2}
+    right = {"b": 3, "c": 4}
+    result = _dict_int_op(left, right, lambda x, y: x + y)
+    assert result == {"a": 1, "b": 5, "c": 4}
+
+
+def test_dict_int_op_subtract() -> None:
+    left = {"a": 5, "b": 10}
+    right = {"a": 2, "b": 3, "c": 1}
+    result = _dict_int_op(left, right, lambda x, y: max(x - y, 0))
+    assert result == {"a": 3, "b": 7, "c": 0}
+
+
+def test_dict_int_op_nested() -> None:
+    left = {"a": 1, "b": {"c": 2, "d": 3}}
+    right = {"a": 2, "b": {"c": 1, "e": 4}}
+    result = _dict_int_op(left, right, lambda x, y: x + y)
+    assert result == {"a": 3, "b": {"c": 3, "d": 3, "e": 4}}
+
+
+def test_dict_int_op_max_depth_exceeded() -> None:
+    left = {"a": {"b": {"c": 1}}}
+    right = {"a": {"b": {"c": 2}}}
+    with pytest.raises(ValueError):
+        _dict_int_op(left, right, lambda x, y: x + y, max_depth=2)
+
+
+def test_dict_int_op_invalid_types() -> None:
+    left = {"a": 1, "b": "string"}
+    right = {"a": 2, "b": 3}
+    with pytest.raises(ValueError):
+        _dict_int_op(left, right, lambda x, y: x + y)