Add StreamTopicTarget.user_ids_muting_topic().

zerver/lib/stream_topic.py

@@ -0,0 +1,28 @@
+from typing import (Dict, List, Text, Set)
+
+from zerver.models import MutedTopic
+
+class StreamTopicTarget(object):
+    '''
+    This class is designed to help us move to a
+    StreamTopic table or something similar.  It isolates
+    places where we are are still using `subject` or
+    `topic_name` as a key into tables.
+    '''
+    def __init__(self, stream_id, topic_name):
+        # type: (int, Text) -> None
+        self.stream_id = stream_id
+        self.topic_name = topic_name
+
+    def user_ids_muting_topic(self):
+        # type: () -> Set[int]
+        query = MutedTopic.objects.filter(
+            stream_id=self.stream_id,
+            topic_name__iexact=self.topic_name,
+        ).values(
+            'user_profile_id',
+        )
+        return {
+            row['user_profile_id']
+            for row in query
+        }

zerver/tests/test_muting.py

@@ -6,7 +6,17 @@ from mock import patch
 from typing import Any, Dict
 
 from zerver.lib.test_classes import ZulipTestCase
-from zerver.models import get_realm, get_user, get_stream, get_recipient, Recipient
+from zerver.lib.stream_topic import StreamTopicTarget
+
+from zerver.models import (
+    get_realm,
+    get_recipient,
+    get_stream,
+    get_user,
+    Recipient,
+    UserProfile,
+)
+
 from zerver.lib.topic_mutes import (
     add_topic_mute,
     get_topic_mutes,
@@ -14,6 +24,40 @@ from zerver.lib.topic_mutes import (
 )
 
 class MutedTopicsTests(ZulipTestCase):
+    def test_user_ids_muting_topic(self):
+        # type: () -> None
+        hamlet = self.example_user('hamlet')
+        cordelia  = self.example_user('cordelia')
+        realm = hamlet.realm
+        stream = get_stream(u'Verona', realm)
+        recipient = get_recipient(Recipient.STREAM, stream.id)
+        topic_name = 'teST topic'
+
+        stream_topic_target = StreamTopicTarget(
+            stream_id=stream.id,
+            topic_name=topic_name,
+        )
+
+        user_ids = stream_topic_target.user_ids_muting_topic()
+        self.assertEqual(user_ids, set())
+
+        def mute_user(user):
+            # type: (UserProfile) -> None
+            add_topic_mute(
+                user_profile=user,
+                stream_id=stream.id,
+                recipient_id=recipient.id,
+                topic_name='test TOPIC',
+            )
+
+        mute_user(hamlet)
+        user_ids = stream_topic_target.user_ids_muting_topic()
+        self.assertEqual(user_ids, {hamlet.id})
+
+        mute_user(cordelia)
+        user_ids = stream_topic_target.user_ids_muting_topic()
+        self.assertEqual(user_ids, {hamlet.id, cordelia.id})
+
     def test_add_muted_topic(self):
         # type: () -> None
         email = self.example_email('hamlet')