Add test and ChangeLog entry for VRc::map_dyn

task-jp · Jul 22, 2022 · 2bf3f83 · 2bf3f83
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diff --git a/helper_crates/vtable/CHANGELOG.md b/helper_crates/vtable/CHANGELOG.md
@@ -1,6 +1,11 @@
 # Changelog
 All notable changes to this crate will be documented in this file.
 
+## [0.1.9] - Unreleased
+
+ - Added `VRc::map_dyn`, the equivalent of `VRc::map` to create a `VRcMapped`
+   when the VRc is already type erased
+
 ## [0.1.8] - 2022-07-05
 
  - Changed the representation of the different types to use NonNull

diff --git a/helper_crates/vtable/tests/test_vrc.rs b/helper_crates/vtable/tests/test_vrc.rs
@@ -233,6 +233,24 @@ fn rc_map_test() {
     assert!(def.upgrade().is_none());
 }
 
+#[test]
+fn rc_map_dyn_test() {
+    fn get_struct_value(instance: &VRcMapped<AppVTable, SomeStruct>) -> u8 {
+        let field_ref = SomeStruct::FIELD_OFFSETS.e.apply_pin(instance.as_pin_ref());
+        *field_ref
+    }
+
+    let app_rc = AppStruct::new();
+    let app_dyn = VRc::into_dyn(app_rc);
+
+    let some_struct_ref = VRc::map_dyn(app_dyn.clone(), |app_dyn| {
+        let app_ref = VRef::downcast_pin(app_dyn).unwrap();
+        AppStruct::FIELD_OFFSETS.some.apply_pin(app_ref)
+    });
+
+    assert_eq!(get_struct_value(&some_struct_ref), 55);
+}
+
 #[test]
 fn rc_map_origin() {
     let app_rc = AppStruct::new();