From d76559ee7c8724d86f975a7eb2fb02fb01686dbb Mon Sep 17 00:00:00 2001
From: Peter Us <ptrusr@gmail.com>
Date: Mon, 31 Jul 2017 13:37:29 +0200
Subject: [PATCH] SNS delete_topic should also delete subscriptions.

---
 moto/sns/models.py                         |  9 ++++++-
 tests/test_sns/test_subscriptions.py       | 31 ++++++++++++++++++++++
 tests/test_sns/test_subscriptions_boto3.py | 30 +++++++++++++++++++++
 3 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/moto/sns/models.py b/moto/sns/models.py
index 5289c8bcd..6d0833476 100644
--- a/moto/sns/models.py
+++ b/moto/sns/models.py
@@ -193,10 +193,17 @@ class SNSBackend(BaseBackend):
             next_token = None
         return values, next_token
 
+    def _get_topic_subscriptions(self, topic):
+        return [sub for sub in self.subscriptions.values() if sub.topic == topic]
+
     def list_topics(self, next_token=None):
         return self._get_values_nexttoken(self.topics, next_token)
 
     def delete_topic(self, arn):
+        topic = self.get_topic(arn)
+        subscriptions = self._get_topic_subscriptions(topic)
+        for sub in subscriptions:
+            self.unsubscribe(sub.arn)
         self.topics.pop(arn)
 
     def get_topic(self, arn):
@@ -222,7 +229,7 @@ class SNSBackend(BaseBackend):
         if topic_arn:
             topic = self.get_topic(topic_arn)
             filtered = OrderedDict(
-                [(k, sub) for k, sub in self.subscriptions.items() if sub.topic == topic])
+                [(sub.arn, sub) for sub in self._get_topic_subscriptions(topic)])
             return self._get_values_nexttoken(filtered, next_token)
         else:
             return self._get_values_nexttoken(self.subscriptions, next_token)
diff --git a/tests/test_sns/test_subscriptions.py b/tests/test_sns/test_subscriptions.py
index c521bb428..292fd83c0 100644
--- a/tests/test_sns/test_subscriptions.py
+++ b/tests/test_sns/test_subscriptions.py
@@ -34,6 +34,37 @@ def test_creating_subscription():
         "ListSubscriptionsResult"]["Subscriptions"]
     subscriptions.should.have.length_of(0)
 
+@mock_sns_deprecated
+def test_deleting_subscriptions_by_deleting_topic():
+    conn = boto.connect_sns()
+    conn.create_topic("some-topic")
+    topics_json = conn.get_all_topics()
+    topic_arn = topics_json["ListTopicsResponse"][
+        "ListTopicsResult"]["Topics"][0]['TopicArn']
+
+    conn.subscribe(topic_arn, "http", "http://example.com/")
+
+    subscriptions = conn.get_all_subscriptions()["ListSubscriptionsResponse"][
+        "ListSubscriptionsResult"]["Subscriptions"]
+    subscriptions.should.have.length_of(1)
+    subscription = subscriptions[0]
+    subscription["TopicArn"].should.equal(topic_arn)
+    subscription["Protocol"].should.equal("http")
+    subscription["SubscriptionArn"].should.contain(topic_arn)
+    subscription["Endpoint"].should.equal("http://example.com/")
+
+    # Now delete the topic
+    conn.delete_topic(topic_arn)
+
+    # And there should now be 0 topics
+    topics_json = conn.get_all_topics()
+    topics = topics_json["ListTopicsResponse"]["ListTopicsResult"]["Topics"]
+    topics.should.have.length_of(0)
+
+    # And there should be zero subscriptions left
+    subscriptions = conn.get_all_subscriptions()["ListSubscriptionsResponse"][
+        "ListSubscriptionsResult"]["Subscriptions"]
+    subscriptions.should.have.length_of(0)
 
 @mock_sns_deprecated
 def test_getting_subscriptions_by_topic():
diff --git a/tests/test_sns/test_subscriptions_boto3.py b/tests/test_sns/test_subscriptions_boto3.py
index 906c483f7..ac325ed20 100644
--- a/tests/test_sns/test_subscriptions_boto3.py
+++ b/tests/test_sns/test_subscriptions_boto3.py
@@ -33,6 +33,36 @@ def test_creating_subscription():
     subscriptions = conn.list_subscriptions()["Subscriptions"]
     subscriptions.should.have.length_of(0)
 
+@mock_sns
+def test_deleting_subscriptions_by_deleting_topic():
+    conn = boto3.client('sns', region_name='us-east-1')
+    conn.create_topic(Name="some-topic")
+    response = conn.list_topics()
+    topic_arn = response["Topics"][0]['TopicArn']
+
+    conn.subscribe(TopicArn=topic_arn,
+                   Protocol="http",
+                   Endpoint="http://example.com/")
+
+    subscriptions = conn.list_subscriptions()["Subscriptions"]
+    subscriptions.should.have.length_of(1)
+    subscription = subscriptions[0]
+    subscription["TopicArn"].should.equal(topic_arn)
+    subscription["Protocol"].should.equal("http")
+    subscription["SubscriptionArn"].should.contain(topic_arn)
+    subscription["Endpoint"].should.equal("http://example.com/")
+
+    # Now delete the topic
+    conn.delete_topic(TopicArn=topic_arn)
+
+    # And there should now be 0 topics
+    topics_json = conn.list_topics()
+    topics = topics_json["Topics"]
+    topics.should.have.length_of(0)
+
+    # And there should be zero subscriptions left
+    subscriptions = conn.list_subscriptions()["Subscriptions"]
+    subscriptions.should.have.length_of(0)
 
 @mock_sns
 def test_getting_subscriptions_by_topic():