fix: deleting non-existent topic shouldn't raise KeyError (#3285)

moto/sns/models.py

@@ -426,7 +426,10 @@ class SNSBackend(BaseBackend):
         return self._get_values_nexttoken(self.topics, next_token)
 
     def delete_topic(self, arn):
-        self.topics.pop(arn)
+        try:
+            self.topics.pop(arn)
+        except KeyError:
+            raise SNSNotFoundError("Topic with arn {0} not found".format(arn))
 
     def get_topic(self, arn):
         try:

tests/test_sns/test_topics.py

@@ -32,6 +32,12 @@ def test_create_and_delete_topic():
     topics.should.have.length_of(0)
 
 
+@mock_sns_deprecated
+def test_delete_non_existent_topic():
+    conn = boto.connect_sns()
+    conn.delete_topic.when.called_with("a-fake-arn").should.throw(BotoServerError)
+
+
 @mock_sns_deprecated
 def test_get_missing_topic():
     conn = boto.connect_sns()

tests/test_sns/test_topics_boto3.py

@@ -35,6 +35,15 @@ def test_create_and_delete_topic():
         topics.should.have.length_of(0)
 
 
+@mock_sns
+def test_delete_non_existent_topic():
+    conn = boto3.client("sns", region_name="us-east-1")
+
+    conn.delete_topic.when.called_with(
+        TopicArn="arn:aws:sns:us-east-1:123456789012:fake-topic"
+    ).should.throw(conn.exceptions.NotFoundException)
+
+
 @mock_sns
 def test_create_topic_with_attributes():
     conn = boto3.client("sns", region_name="us-east-1")