diff --git a/zulip_bots/zulip_bots/bots/yoda/fixtures/test_api_key_error.json b/zulip_bots/zulip_bots/bots/yoda/fixtures/test_api_key_error.json
new file mode 100644
index 0000000..352d7f7
--- /dev/null
+++ b/zulip_bots/zulip_bots/bots/yoda/fixtures/test_api_key_error.json
@@ -0,0 +1,14 @@
+{
+  "request": {
+    "api_url": "https://yoda.p.mashape.com/yoda?sentence=You+will+learn+how+to+speak+like+me+someday.",
+    "headers": {
+      "X-Mashape-Key": "12345678",
+      "Accept": "text/plain"
+    }
+  },
+  "response": {},
+  "response-headers": {
+    "status": 403,
+    "content-type": "text/html; charset=utf-8"
+  }
+}
diff --git a/zulip_bots/zulip_bots/bots/yoda/fixtures/test_service_unavailable_error.json b/zulip_bots/zulip_bots/bots/yoda/fixtures/test_service_unavailable_error.json
new file mode 100644
index 0000000..245f369
--- /dev/null
+++ b/zulip_bots/zulip_bots/bots/yoda/fixtures/test_service_unavailable_error.json
@@ -0,0 +1,14 @@
+{
+  "request": {
+    "api_url": "https://yoda.p.mashape.com/yoda?sentence=You+will+learn+how+to+speak+like+me+someday.",
+    "headers": {
+      "X-Mashape-Key": "12345678",
+      "Accept": "text/plain"
+    }
+  },
+  "response": {},
+  "response-headers": {
+    "status": 503,
+    "content-type": "text/html; charset=utf-8"
+  }
+}
diff --git a/zulip_bots/zulip_bots/bots/yoda/fixtures/test_unknown_error.json b/zulip_bots/zulip_bots/bots/yoda/fixtures/test_unknown_error.json
new file mode 100644
index 0000000..43c8b4c
--- /dev/null
+++ b/zulip_bots/zulip_bots/bots/yoda/fixtures/test_unknown_error.json
@@ -0,0 +1,16 @@
+{
+  "request": {
+    "api_url": "https://yoda.p.mashape.com/yoda?sentence=You+will+learn+how+to+speak+like+me+someday.",
+    "headers": {
+      "X-Mashape-Key": "12345678",
+      "Accept": "text/plain"
+    }
+  },
+  "response": {
+      "message": "Unknown Error."
+  },
+  "response-headers": {
+    "status": 123,
+    "content-type": "text/html; charset=utf-8"
+  }
+}
diff --git a/zulip_bots/zulip_bots/bots/yoda/test_yoda.py b/zulip_bots/zulip_bots/bots/yoda/test_yoda.py
index c516db7..fee9931 100644
--- a/zulip_bots/zulip_bots/bots/yoda/test_yoda.py
+++ b/zulip_bots/zulip_bots/bots/yoda/test_yoda.py
@@ -1,3 +1,4 @@
+from zulip_bots.bots.yoda.yoda import ServiceUnavailableError
 from zulip_bots.test_lib import BotTestCase
 
 class TestYodaBot(BotTestCase):
@@ -51,3 +52,19 @@ class TestYodaBot(BotTestCase):
         self._test('@#$%^&*',
                    "Invalid input, please check the sentence you have entered.",
                    'test_invalid_input')
+
+        # Test 403 response.
+        self._test('You will learn how to speak like me someday.',
+                   "Invalid Api Key. Did you follow the instructions in the `readme.md` file?",
+                   'test_api_key_error')
+
+        # Test 503 response.
+        with self.assertRaises(ServiceUnavailableError):
+            self._test('You will learn how to speak like me someday.',
+                       "The service is temporarily unavailable, please try again.",
+                       'test_service_unavailable_error')
+
+        # Test unknown response.
+        self._test('You will learn how to speak like me someday.',
+                   "Unknown Error.Error code: 123 Did you follow the instructions in the `readme.md` file?",
+                   'test_unknown_error')
diff --git a/zulip_bots/zulip_bots/bots/yoda/yoda.py b/zulip_bots/zulip_bots/bots/yoda/yoda.py
index d5fd9aa..5e77f53 100644
--- a/zulip_bots/zulip_bots/bots/yoda/yoda.py
+++ b/zulip_bots/zulip_bots/bots/yoda/yoda.py
@@ -72,7 +72,7 @@ class YodaSpeakHandler(object):
             error_message = response.json()['message']
             logging.error(error_message)
             error_code = response.status_code
-            error_message = error_message + 'Error code: ' + error_code +\
+            error_message = error_message + 'Error code: ' + str(error_code) +\
                 ' Did you follow the instructions in the `readme.md` file?'
             return error_message