From 02357faf03c4d4b362d3283a428fc51a002c7dc1 Mon Sep 17 00:00:00 2001
From: Alex Root Junior <jroot.junior@gmail.com>
Date: Tue, 27 Sep 2022 23:35:36 +0300
Subject: [PATCH] Fixed #1013: Empty mention should be None instead of empty
 string.

---
 CHANGES/1013.bugfix.rst            |  1 +
 aiogram/filters/command.py         |  5 ++++-
 tests/test_filters/test_command.py | 17 +++++++++++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 CHANGES/1013.bugfix.rst

diff --git a/CHANGES/1013.bugfix.rst b/CHANGES/1013.bugfix.rst
new file mode 100644
index 00000000..3b8e1645
--- /dev/null
+++ b/CHANGES/1013.bugfix.rst
@@ -0,0 +1 @@
+Fixed empty mention in command parsing, now it will be None instead of an empty string
diff --git a/aiogram/filters/command.py b/aiogram/filters/command.py
index b46ca80d..4d8a0143 100644
--- a/aiogram/filters/command.py
+++ b/aiogram/filters/command.py
@@ -132,7 +132,10 @@ class Command(Filter):
         # "/command@mention" -> "/", ("command", "@", "mention")
         prefix, (command, _, mention) = full_command[0], full_command[1:].partition("@")
         return CommandObject(
-            prefix=prefix, command=command, mention=mention, args=args[0] if args else None
+            prefix=prefix,
+            command=command,
+            mention=mention or None,
+            args=args[0] if args else None,
         )
 
     def validate_prefix(self, command: CommandObject) -> None:
diff --git a/tests/test_filters/test_command.py b/tests/test_filters/test_command.py
index e1c296ed..1cdd0b70 100644
--- a/tests/test_filters/test_command.py
+++ b/tests/test_filters/test_command.py
@@ -104,6 +104,23 @@ class TestCommandFilter:
         assert "args" in result
         assert result["args"] == "42"
 
+    async def test_empty_mention_is_none(self, bot: MockedBot):
+        # Fixed https://github.com/aiogram/aiogram/issues/1013:
+        #   Empty mention should be None instead of empty string.
+
+        message = Message(
+            message_id=0,
+            text="/test",
+            chat=Chat(id=42, type="private"),
+            date=datetime.datetime.now(),
+        )
+        command = Command("test")
+        result = await command(message=message, bot=bot)
+
+        assert "command" in result
+        command_obj: CommandObject = result["command"]
+        assert command_obj.mention is None
+
 
 class TestCommandObject:
     @pytest.mark.parametrize(