feat: sync ephemeral bot demo commands

Sync telesrv 172a86e (feat(bot-demo): echo ephemeral group commands).

Skipped telesrv docs changes per public sync rules.

cmd/bots/ptbecho/test_echo.py

@@ -0,0 +1,70 @@
+import unittest
+from types import SimpleNamespace
+
+import echo
+
+
+class FakeMessage:
+    def __init__(self, *, text="hello", ephemeral_id=None):
+        self.text = text
+        self.caption = None
+        self.chat_id = -1000000000002
+        self.from_user = SimpleNamespace(id=1780243200)
+        self.api_kwargs = {}
+        if ephemeral_id is not None:
+            self.api_kwargs["ephemeral_message_id"] = ephemeral_id
+        self.replies = []
+
+    async def reply_text(self, text):
+        self.replies.append(text)
+        return SimpleNamespace(message_id=1, api_kwargs={})
+
+
+class FakeBot:
+    def __init__(self):
+        self.calls = []
+
+    async def send_message(self, **kwargs):
+        self.calls.append(kwargs)
+        return SimpleNamespace(
+            message_id=0,
+            api_kwargs={"ephemeral_message_id": 88},
+        )
+
+
+class EchoTest(unittest.IsolatedAsyncioTestCase):
+    async def test_ephemeral_echo_uses_receiver_and_transient_reply(self):
+        message = FakeMessage(text="/private@TetrisBot", ephemeral_id=77)
+        bot = FakeBot()
+
+        await echo.send_echo(message, bot, "echo: ", "ephemeral echo: ")
+
+        self.assertEqual(message.replies, [])
+        self.assertEqual(
+            bot.calls,
+            [{
+                "chat_id": -1000000000002,
+                "text": "ephemeral echo: /private@TetrisBot",
+                "api_kwargs": {
+                    "receiver_user_id": 1780243200,
+                    "reply_parameters": {"ephemeral_message_id": 77},
+                },
+            }],
+        )
+
+    async def test_normal_echo_stays_on_standard_reply_path(self):
+        message = FakeMessage()
+        bot = FakeBot()
+
+        await echo.send_echo(message, bot, "echo: ", "ephemeral echo: ")
+
+        self.assertEqual(message.replies, ["echo: hello"])
+        self.assertEqual(bot.calls, [])
+
+    def test_invalid_ephemeral_id_is_not_accepted(self):
+        self.assertIsNone(echo.ephemeral_message_id(FakeMessage(ephemeral_id=0)))
+        self.assertIsNone(echo.ephemeral_message_id(FakeMessage(ephemeral_id=True)))
+
+
+if __name__ == "__main__":
+    unittest.main()