adds data service cache tests

tests/data_service/test_data_service_cache.py

@@ -0,0 +1,33 @@
+import logging
+
+import pydase
+from pydase.data_service.data_service_cache import DataServiceCache
+from pydase.utils.helpers import get_nested_value_from_DataService_by_path_and_key
+
+logger = logging.getLogger()
+
+
+def test_nested_attributes_cache_callback() -> None:
+    class SubClass(pydase.DataService):
+        name = "Hello"
+
+    class ServiceClass(pydase.DataService):
+        class_attr = SubClass()
+        name = "World"
+
+    test_service = ServiceClass()
+    cache = DataServiceCache(test_service)
+
+    test_service.name = "Peepz"
+    assert (
+        get_nested_value_from_DataService_by_path_and_key(cache.cache, "name")
+        == "Peepz"
+    )
+
+    test_service.class_attr.name = "Ciao"
+    assert (
+        get_nested_value_from_DataService_by_path_and_key(
+            cache.cache, "class_attr.name"
+        )
+        == "Ciao"
+    )