messages: Add Addressee.for_user_ids().

This commit is a part of our efforts surrounding #9474.

zerver/lib/addressee.py

@@ -9,6 +9,7 @@ from zerver.models import (
     Realm,
     UserProfile,
     get_user_including_cross_realm,
+    get_user_by_id_in_realm_including_cross_realm,
 )
 
 def raw_pm_with_emails(email_str: str, my_email: str) -> List[str]:
@@ -31,6 +32,16 @@ def get_user_profiles(emails: Iterable[str], realm: Realm) -> List[UserProfile]:
         user_profiles.append(user_profile)
     return user_profiles
 
+def get_user_profiles_by_ids(user_ids: Iterable[int], realm: Realm) -> List[UserProfile]:
+    user_profiles = []  # type: List[UserProfile]
+    for user_id in user_ids:
+        try:
+            user_profile = get_user_by_id_in_realm_including_cross_realm(user_id, realm)
+        except UserProfile.DoesNotExist:
+            raise JsonableError(_("Invalid user ID {}".format(user_id)))
+        user_profiles.append(user_profile)
+    return user_profiles
+
 class Addressee:
     # This is really just a holder for vars that tended to be passed
     # around in a non-type-safe way before this class was introduced.
@@ -130,6 +141,14 @@ class Addressee:
             user_profiles=user_profiles,
         )
 
+    @staticmethod
+    def for_user_ids(user_ids: Sequence[int], realm: Realm) -> 'Addressee':
+        user_profiles = get_user_profiles_by_ids(user_ids, realm)
+        return Addressee(
+            msg_type='private',
+            user_profiles=user_profiles,
+        )
+
     @staticmethod
     def for_user_profile(user_profile: UserProfile) -> 'Addressee':
         user_profiles = [user_profile]

zerver/tests/test_messages.py

@@ -277,7 +277,6 @@ class TopicHistoryTest(ZulipTestCase):
         result = self.client_get(endpoint, dict())
         self.assert_json_error(result, 'Invalid stream id')
 
-
 class TestCrossRealmPMs(ZulipTestCase):
     def make_realm(self, domain: str) -> Realm:
         realm = Realm.objects.create(string_id=domain, invite_required=False)
@@ -391,6 +390,29 @@ class TestCrossRealmPMs(ZulipTestCase):
             self.send_huddle_message(user1_email, [user2_email, user3_email],
                                      sender_realm="1.example.com")
 
+class TestAddressee(ZulipTestCase):
+    def test_addressee_for_user_ids(self) -> None:
+        realm = get_realm('zulip')
+        user_ids = [self.example_user('cordelia').id,
+                    self.example_user('hamlet').id,
+                    self.example_user('othello').id]
+
+        result = Addressee.for_user_ids(user_ids=user_ids, realm=realm)
+        user_profiles = result.user_profiles()
+        result_user_ids = [user_profiles[0].id, user_profiles[1].id,
+                           user_profiles[2].id]
+
+        self.assertEqual(set(result_user_ids), set(user_ids))
+
+    def test_addressee_for_user_ids_nonexistent_id(self) -> None:
+        def assert_invalid_user_id() -> Any:
+            return self.assertRaisesRegex(
+                JsonableError,
+                'Invalid user ID ')
+
+        with assert_invalid_user_id():
+            Addressee.for_user_ids(user_ids=[779], realm=get_realm('zulip'))
+
 class InternalPrepTest(ZulipTestCase):
 
     def test_returns_for_internal_sends(self) -> None: