models: Add can_invite_others_to_realm for checking who can send invites.

This commit adds can_invite_others_to_realm helper which will be used in
further in next commit when invite_to_realm_policy will be modified to
support all values of COMMON_POLICY_TYPES.

It is important for this commit's correctness that
INVITE_TO_REALM_POLICY_TYPES was initialized to use the same values.

zerver/models.py

@@ -1522,7 +1522,11 @@ class UserProfile(AbstractBaseUser, PermissionsMixin):
         return False
 
     def has_permission(self, policy_name: str) -> bool:
-        if policy_name not in ["create_stream_policy", "invite_to_stream_policy"]:
+        if policy_name not in [
+            "create_stream_policy",
+            "invite_to_stream_policy",
+            "invite_to_realm_policy",
+        ]:
             raise AssertionError("Invalid policy")
 
         if self.is_realm_admin:
@@ -1553,6 +1557,9 @@ class UserProfile(AbstractBaseUser, PermissionsMixin):
     def can_subscribe_other_users(self) -> bool:
         return self.has_permission("invite_to_stream_policy")
 
+    def can_invite_others_to_realm(self) -> bool:
+        return self.has_permission("invite_to_realm_policy")
+
     def can_access_public_streams(self) -> bool:
         return not (self.is_guest or self.realm.is_zephyr_mirror_realm)
 

zerver/tests/test_signup.py

@@ -1232,6 +1232,14 @@ class InviteUserTest(InviteUserBase):
         self.assertTrue(find_key_by_email(email2))
         self.check_sent_emails([email, email2], custom_from_name="Hamlet")
 
+    def test_can_invite_others_to_realm(self) -> None:
+        othello = self.example_user("othello")
+
+        def validation_func() -> bool:
+            return othello.can_invite_others_to_realm()
+
+        self.check_has_permission_policies(othello, "invite_to_realm_policy", validation_func)
+
     def test_require_realm_admin(self) -> None:
         """
         The invite_to_realm_policy realm setting works properly.