diff --git a/tests/test_nested_set.py b/tests/test_nested_set.py
new file mode 100644
index 0000000..3cffffa
--- /dev/null
+++ b/tests/test_nested_set.py
@@ -0,0 +1,63 @@
+from typing import Any, List
+
+import pytest
+
+from libbot import sync
+
+
+@pytest.mark.parametrize(
+    "target, value, path, create_missing, expected",
+    [
+        ({"foo": "bar"}, "rab", ["foo"], True, {"foo": "rab"}),
+        ({"foo": "bar"}, {"123": 456}, ["foo"], True, {"foo": {"123": 456}}),
+        (
+            {"foo": {"bar": {}}},
+            True,
+            ["foo", "bar", "test"],
+            True,
+            {"foo": {"bar": {"test": True}}},
+        ),
+        (
+            {"foo": {"bar": {}}},
+            True,
+            ["foo", "bar", "test"],
+            False,
+            {"foo": {"bar": {}}},
+        ),
+    ],
+)
+def test_nested_set_valid(
+    target: dict[str, Any],
+    value: Any,
+    path: List[str],
+    create_missing: bool,
+    expected: Any,
+):
+    assert (
+        sync.nested_set(target, value, *path, create_missing=create_missing)
+    ) == expected
+
+
+@pytest.mark.parametrize(
+    "target, value, path, create_missing, expected",
+    [
+        (
+            {"foo": {"bar": {}}},
+            True,
+            ["foo", "bar", "test1", "test2"],
+            False,
+            KeyError,
+        ),
+    ],
+)
+def test_nested_set_invalid(
+    target: dict[str, Any],
+    value: Any,
+    path: List[str],
+    create_missing: bool,
+    expected: Any,
+):
+    with pytest.raises(expected):
+        assert (
+            sync.nested_set(target, value, *path, create_missing=create_missing)
+        ) == expected