Return DataMixin

tests/test_utils/test_mixins.py

@@ -1,11 +1,45 @@
 import pytest
 
-from aiogram.utils.mixins import ContextInstanceMixin
+from aiogram.utils.mixins import (
+    ContextInstanceMixin,
+    DataMixin,
+)
+
 
 class ContextObject(ContextInstanceMixin['ContextObject']):
     pass
 
 
+class DataObject(DataMixin):
+    pass
+
+
+class TestDataMixin:
+    def test_store_value(self):
+        obj = DataObject()
+        obj["foo"] = 42
+
+        assert "foo" in obj
+        assert obj["foo"] == 42
+        assert len(obj.data) == 1
+
+    def test_remove_value(self):
+        obj = DataObject()
+        obj["foo"] = 42
+        del obj["foo"]
+
+        assert "key" not in obj
+        assert len(obj.data) == 0
+
+    def test_getter(self):
+        obj = DataObject()
+        obj["foo"] = 42
+
+        assert obj.get("foo") == 42
+        assert obj.get("bar") is None
+        assert obj.get("baz", "test") == "test"
+
+
 class TestContextInstanceMixin:
     def test_empty(self):
         obj = ContextObject()