test: include probability in sad message testing

bot.py

@@ -188,6 +188,9 @@ def __init__(self):
                 "You might need to specify one or more environment variables."
             )
 
+        # Probability to avoid overcrowding Telegram chats with dog pictures
+        self.sad_message_response_probability: float = 0.45
+
         # Fetches list of dog breeds from the Dogs API
         self.fetch_breeds()
 
@@ -307,8 +310,14 @@ async def handle_text_messages(self, update, context):
         elif has_wolf_reference:
             await self.send_wolf_picture(update, context)
         elif is_sad_message:
-            sad_caption = "Don't be sad, have a cute dog!"
-            await self.send_dog_picture(update, context, mentioned_breed, sad_caption)
+            # Easter Egg: if the message is sad, send a dog picture
+            # with a comforting message
+
+            # To avoid overloading the chat with dog pictures, only
+            # send a picture with a certain probability
+            if random.random() < self.sad_message_response_probability:
+                sad_caption = "Don't be sad, have a cute dog!"
+                await self.send_dog_picture(update, context, mentioned_breed, sad_caption)
         elif any([should_trigger_picture, is_personal_chat, mentions_a_breed]):
             await self.send_dog_picture(update, context, mentioned_breed)
 

tests.py

@@ -423,25 +423,34 @@ async def test_handle_text_messages_for_sad_message(
     message, the bot replies with a dog picture and a particular caption.
     """
 
-    # instantiating mock bot
-    bot = get_mock_bot(monkeypatch)
-    update = get_mock_update(message=sad_message)
-    context = get_mock_context()
-
-    # context is empty of sent photos
-    assert len(context.bot.photos) == 0
-
-    await bot.handle_text_messages(update, context)
-
-    # one picture sent through context
-    assert len(context.bot.photos) == 1
-
-    # contains the chat_id, original message id, photo url and caption
-    chat_id, reply_to_message_id, photo_url, caption = context.bot.photos[0]
-    assert chat_id == update.message.chat_id
-    assert reply_to_message_id == update.message.message_id
-    assert photo_url == "https://dog.pics/dog.png"
-    assert caption == "Don't be sad, have a cute dog!"
+    for probability in [0.0, 1.0]:
+        # we're either testing with a 100% probability or a 0% probability
+        # so we can assert the outcome of the test
+        should_send: bool = probability == 1.0
+
+        # instantiating mock bot
+        bot = get_mock_bot(monkeypatch)
+        bot.sad_message_response_probability = probability
+        update = get_mock_update(message=sad_message)
+        context = get_mock_context()
+
+        # context is empty of sent photos
+        assert len(context.bot.photos) == 0
+
+        await bot.handle_text_messages(update, context)
+
+        if should_send:
+            # one picture sent through context
+            assert len(context.bot.photos) == 1
+
+            # contains the chat_id, original message id, photo url and caption
+            chat_id, reply_to_message_id, photo_url, caption = context.bot.photos[0]
+            assert chat_id == update.message.chat_id
+            assert reply_to_message_id == update.message.message_id
+            assert photo_url == "https://dog.pics/dog.png"
+            assert caption == "Don't be sad, have a cute dog!"
+        else:
+            assert len(context.bot.photos) == 0
 
 
 @pytest.mark.parametrize(