AIOG-T-51. TelegramObject property bot added

* property added
 * unit tests added
 * local import used to avoid circular reference

aiogram/api/types/base.py

@@ -1,9 +1,15 @@
+from __future__ import annotations
+
 import datetime
+import typing
 
 from pydantic import BaseModel, Extra
 
 from aiogram.utils.mixins import ContextInstanceMixin
 
+if typing.TYPE_CHECKING:
+    from ..client.bot import Bot  # pragma: no cover
+
 
 class TelegramObject(ContextInstanceMixin["TelegramObject"], BaseModel):
     class Config:
@@ -15,6 +21,19 @@ class TelegramObject(ContextInstanceMixin["TelegramObject"], BaseModel):
         allow_population_by_field_name = True
         json_encoders = {datetime.datetime: lambda dt: int(dt.timestamp())}
 
+    @property
+    def bot(self) -> Bot:
+        from ..client.bot import Bot
+
+        bot = Bot.get_current()
+        if bot is None:
+            raise RuntimeError(
+                "Can't get bot instance from context. "
+                "You can fix it with setting current instance: "
+                "'Bot.set_current(bot_instance)'"
+            )
+        return bot
+
 
 class MutableTelegramObject(TelegramObject):
     class Config:

tests/test_api/test_types/test_telegram_object.py

@@ -0,0 +1,21 @@
+import pytest
+
+from aiogram import Bot
+from aiogram.api.types import TelegramObject
+
+
+class TestTelegramObject:
+    @pytest.fixture()
+    def context_cleanup(self):
+        yield
+        Bot.reset_current(self.__token)
+
+    @pytest.mark.usefixtures("context_cleanup")
+    def test_bot_property_positive(self):
+        self.__token = Bot.set_current(Bot("42:TEST"))
+
+        assert isinstance(TelegramObject().bot, Bot)
+
+    def test_bot_property_negative(self):
+        with pytest.raises(RuntimeError, match=r"Bot.set_current\(bot_instance\)"):
+            isinstance(TelegramObject().bot, Bot)