task: add tests for spawn_local in panic scenarios (#7694)

Signed-off-by: ADD-SP <[email protected]>

tokio-util/tests/task_join_map.rs

@@ -438,6 +438,24 @@ async fn duplicate_keys_drop() {
 mod spawn_local {
     use super::*;
 
+    #[test]
+    #[should_panic(
+        expected = "`spawn_local` called from outside of a `task::LocalSet` or `runtime::LocalRuntime`"
+    )]
+    fn panic_outside_any_runtime() {
+        let mut map = JoinMap::new();
+        map.spawn_local((), async {});
+    }
+
+    #[tokio::test(flavor = "multi_thread")]
+    #[should_panic(
+        expected = "`spawn_local` called from outside of a `task::LocalSet` or `runtime::LocalRuntime`"
+    )]
+    async fn panic_in_multi_thread_runtime() {
+        let mut map = JoinMap::new();
+        map.spawn_local((), async {});
+    }
+
     #[cfg(tokio_unstable)]
     mod local_runtime {
         use super::*;