Add test for try user delegation

Author: Sakib25800

src/bors/handlers/review.rs

@@ -831,4 +831,34 @@ approve = ["+approved"]
             })
             .await;
     }
+
+    #[sqlx::test]
+    async fn delegate_insufficient_permission_try_user(pool: sqlx::PgPool) {
+        let world = World::default();
+        let try_user = User::new(200, "try-user");
+        world.default_repo().lock().permissions = Permissions::default();
+        world
+            .default_repo()
+            .lock()
+            .permissions
+            .users
+            .insert(try_user.clone(), vec![PermissionType::Try]);
+
+        BorsBuilder::new(pool)
+            .world(world)
+            .run_test(|mut tester| async {
+                tester
+                    .post_comment(Comment::from("@bors delegate+").with_author(try_user))
+                    .await?;
+                assert_eq!(
+                    tester.get_comment().await?,
+                    "@try-user: :key: Insufficient privileges: not in review users"
+                );
+
+                let pr = tester.get_default_pr().await?;
+                assert!(!pr.delegated);
+                Ok(tester)
+            })
+            .await;
+    }
 }