Add one more test for cell assign

arcshift/src/lib.rs

@@ -421,8 +421,9 @@ impl<T: 'static> ArcShiftCell<T> {
     /// This method is very fast, basically the speed of a regular reference, unless
     /// the value has been modified by calling one of the update-methods.
     ///
-    /// This method will drop older values which are no longer needed
+    /// This method will do a reload (drop older values which are no longer needed).
     /// This method is reentrant - you are allowed to call it from within the closure 'f'.
+    /// However, only the outermost invocation will cause a reload.
     pub fn get(&self, f: impl FnOnce(&T)) {
         self.recursion.set(self.recursion.get() + 1);
         let val = if self.recursion.get() == 1 {

arcshift/src/tests.rs

@@ -195,7 +195,25 @@ fn simple_cell_recursion() {
         owner.validate();
     });
 }
+#[test]
+fn simple_cell_assign() {
+    model(|| {
+        let owner = SpyOwner2::new();
+        {
+            let cell = ArcShiftCell::new(owner.create("original"));
+            let new_value = ArcShift::new(owner.create("new"));
+
+            cell.get(|val| {
+                assert_eq!(val.str(), "original");
+                assert!(cell.assign(&ArcShift::new(owner.create("dummy"))).is_err());
+            });
+
+            cell.assign(&new_value).unwrap();
 
+            cell.get(|val| assert_eq!(val.str(), "new"));
+        }
+    });
+}
 #[test]
 fn simple_rcu() {
     model(|| {