From f34b1b78cf80124d4f922a2627f3229100146490 Mon Sep 17 00:00:00 2001
From: Jakob Hellermann <jakob.hellermann@protonmail.com>
Date: Fri, 28 Oct 2022 12:07:55 +0200
Subject: [PATCH] add test checking that as_readonly works as expected

---
 crates/bevy_ecs/src/query/state.rs | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/crates/bevy_ecs/src/query/state.rs b/crates/bevy_ecs/src/query/state.rs
index 5ca6311d960f38..0d2b60c9922237 100644
--- a/crates/bevy_ecs/src/query/state.rs
+++ b/crates/bevy_ecs/src/query/state.rs
@@ -1427,6 +1427,33 @@ mod tests {
         }
     }
 
+    #[test]
+    fn query_state_with_config_as_readonly() {
+        let mut world = World::new();
+
+        let num = 42;
+
+        let component_id = world.init_component::<TestComponent>();
+        let spawned_entity = world.spawn(TestComponent(num)).id();
+
+        let mut query_state = QueryState::<(Entity, PtrMut<'_>), ()>::new_with_config(
+            &mut world,
+            ((), component_id),
+            (),
+        );
+
+        let results: Vec<_> = query_state.iter(&world).collect();
+        match results.as_slice() {
+            [(entity, value)] => {
+                assert_eq!(*entity, spawned_entity);
+                // SAFETY: correct type, read access
+                let value = unsafe { value.deref::<TestComponent>() };
+                assert_eq!(value.0, num);
+            }
+            _ => panic!("expected to get one result"),
+        }
+    }
+
     #[test]
     fn query_state_with_config_vec() {
         let mut world = World::new();