fix: Observable.value setter (covariant) (#993)

* fix(observable): check if new value is an instance of WillChangeNotification unchanged before setting it

* chore(observable): Bump version to 2.3.2 and update CHANGELOG.md with bug fix for Observable value setter

mobx/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.3.2
+
+- Fix Observable.value setter when class with operator ==(covariant) is used as a value
+
 ## 2.3.1
 
 - Fix preserving stacktrace in Computed and Reaction when exception thrown inside argument function

mobx/lib/src/core/observable.dart

@@ -61,7 +61,8 @@ class Observable<T> extends Atom
     final oldValue = _value;
     final newValueDynamic = _prepareNewValue(value);
 
-    if (newValueDynamic == WillChangeNotification.unchanged) {
+    if (newValueDynamic is WillChangeNotification &&
+        newValueDynamic == WillChangeNotification.unchanged) {
       return;
     }
     final newValue = newValueDynamic as T;

mobx/lib/version.dart

@@ -1,4 +1,4 @@
 // Generated via set_version.dart. !!!DO NOT MODIFY BY HAND!!!
 
 /// The current version as per `pubspec.yaml`.
-const version = '2.3.1';
+const version = '2.3.2';

mobx/pubspec.yaml

@@ -1,5 +1,5 @@
 name: mobx
-version: 2.3.1
+version: 2.3.2
 description: "MobX is a library for reactively managing the state of your applications. Use the power of observables, actions, and reactions to supercharge your Dart and Flutter apps."
 
 repository: https://github.com/mobxjs/mobx.dart

mobx/test/observable_test.dart

@@ -80,6 +80,11 @@ void main() {
       x.value = 100;
       expect(x.nonObservableValue, 100);
     });
+
+    test('set value covariant', () async {
+      final x = Observable<_Covariant?>(null);
+      x.value = _Covariant();
+    });
   });
 
   group('createAtom()', () {
@@ -111,3 +116,13 @@ void main() {
     });
   });
 }
+
+class _Covariant {
+  @override
+  // ignore: hash_and_equals
+  bool operator ==(covariant _Covariant other) {
+    if (identical(this, other)) return true;
+
+    return other is _Covariant;
+  }
+}