youtube: Add test for unknown error during initialize.

zulip_bots/zulip_bots/bots/youtube/fixtures/test_unknown_error.json

@@ -0,0 +1,31 @@
+{
+    "request": {
+      "api_url": "https://www.googleapis.com/youtube/v3/search",
+      "params": {
+        "part": "id,snippet",
+        "maxResults": 1,
+        "key": "12345678",
+        "q": "test",
+        "alt": "json",
+        "type": "video",
+        "regionCode": "US"
+      }
+    },
+    "response": {
+      "error": {
+        "errors": [
+          {
+            "domain": "error",
+            "reason": "unknownError",
+            "message": "Unknown Rrror"
+          }
+        ],
+        "code": 400,
+        "message": "Bad Request"
+      }
+    },
+    "response-headers": {
+      "status": 400,
+      "content-type": "application/json; charset=utf-8"
+    }
+  }

zulip_bots/zulip_bots/bots/youtube/test_youtube.py

@@ -43,6 +43,15 @@ class TestYoutubeBot(BotTestCase, DefaultTests):
                 self.assertRaises(bot_handler.BotQuitException):
                     bot.initialize(bot_handler)
 
+    def test_unknown_error(self) -> None:
+        bot = get_bot_message_handler(self.bot_name)
+        bot_handler = StubBotHandler()
+
+        with self.mock_config_info(self.normal_config), \
+                self.mock_http_conversation('test_unknown_error'), \
+                self.assertRaises(HTTPError):
+                    bot.initialize(bot_handler)
+
     def test_multiple(self) -> None:
         bot = get_bot_message_handler(self.bot_name)
         bot_handler = StubBotHandler()