Fix Empty Captions not Being Passed by Bot.copy_message (#2651)

AUTHORS.rst

@@ -39,6 +39,7 @@ The following wonderful people contributed directly or indirectly to this projec
 - `daimajia <https://github.com/daimajia>`_
 - `Daniel Reed <https://github.com/nmlorg>`_
 - `D David Livingston <https://github.com/daviddl9>`_
+- `DonalDuck004 <https://github.com/DonalDuck004>`_
 - `Eana Hufwe <https://github.com/blueset>`_
 - `Ehsan Online <https://github.com/ehsanonline>`_
 - `Eli Gao <https://github.com/eligao>`_

telegram/bot.py

@@ -5296,7 +5296,7 @@ class Bot(TelegramObject):
             'disable_notification': disable_notification,
             'allow_sending_without_reply': allow_sending_without_reply,
         }
-        if caption:
+        if caption is not None:
             data['caption'] = caption
         if caption_entities:
             data['caption_entities'] = caption_entities

tests/test_bot.py

@@ -2024,7 +2024,8 @@ class TestBot:
 
     @flaky(3, 1)
     @pytest.mark.parametrize('json_keyboard', [True, False])
-    def test_copy_message(self, monkeypatch, bot, chat_id, media_message, json_keyboard):
+    @pytest.mark.parametrize('caption', ["<b>Test</b>", '', None])
+    def test_copy_message(self, monkeypatch, bot, chat_id, media_message, json_keyboard, caption):
         keyboard = InlineKeyboardMarkup(
             [[InlineKeyboardButton(text="test", callback_data="test2")]]
         )
@@ -2033,7 +2034,7 @@ class TestBot:
             assert data["chat_id"] == chat_id
             assert data["from_chat_id"] == chat_id
             assert data["message_id"] == media_message.message_id
-            assert data["caption"] == "<b>Test</b>"
+            assert data.get("caption") == caption
             assert data["parse_mode"] == ParseMode.HTML
             assert data["reply_to_message_id"] == media_message.message_id
             assert data["reply_markup"] == keyboard.to_json()
@@ -2046,7 +2047,7 @@ class TestBot:
             chat_id,
             from_chat_id=chat_id,
             message_id=media_message.message_id,
-            caption="<b>Test</b>",
+            caption=caption,
             caption_entities=[MessageEntity(MessageEntity.BOLD, 0, 4)],
             parse_mode=ParseMode.HTML,
             reply_to_message_id=media_message.message_id,