fixes #1997

packages/riverpod/CHANGELOG.md

@@ -2,6 +2,7 @@
 
 - Update dependencies.
 - fixes an exception on newer Dart versions
+- fixes an edge-case where `FutureProvider`/`AsyncNotifier` did not emit the new state when the created `Future` completed (#1997)
 
 ## 2.1.1
 

packages/riverpod/lib/src/async_notifier/base.dart

@@ -173,8 +173,6 @@ mixin FutureHandlerProviderElementMixin<T>
   }
 
   void _dataTransition(T value) {
-    _builtFuture = null;
-
     final completer = _futureCompleter;
     if (completer != null) {
       completer.complete(value);
@@ -192,8 +190,6 @@ mixin FutureHandlerProviderElementMixin<T>
   }
 
   void _errorTransition(Object err, StackTrace stackTrace) {
-    _builtFuture = null;
-
     final completer = _futureCompleter;
     if (completer != null) {
       completer
@@ -253,7 +249,6 @@ mixin FutureHandlerProviderElementMixin<T>
               if (_builtFuture == futureOr) {
                 _errorTransition(error, stackTrace);
                 setState(AsyncError<T>(error, stackTrace));
-                _builtFuture = null;
               }
             },
           );
@@ -295,7 +290,6 @@ mixin FutureHandlerProviderElementMixin<T>
         );
       }
     }
-
     super.dispose();
   }
 

packages/riverpod/test/providers/async_notifier/async_notifier_test.dart

@@ -509,7 +509,7 @@ void main() {
         });
 
         test(
-          'after manually going back to loading, dispose throws StateError',
+          'after manually going back to loading, resolves with last future result',
           () async {
             final container = createContainer();
             final completer = Completer<int>.sync();
@@ -527,6 +527,30 @@ void main() {
 
             completer.complete(42);
 
+            await expectLater(future, completion(42));
+          },
+        );
+
+        test(
+          'if going back to loading after future resolved, throws StateError',
+          () async {
+            final container = createContainer();
+            final completer = Completer<int>.sync();
+            final provider = factory.simpleTestProvider<int>(
+              (ref) => completer.future,
+            );
+
+            container.read(provider);
+
+            completer.complete(42);
+
+            container.read(provider.notifier).state = const AsyncData(42);
+            container.read(provider.notifier).state = const AsyncLoading<int>();
+
+            final future = container.read(provider.future);
+
+            container.dispose();
+
             await expectLater(future, throwsStateError);
           },
         );
@@ -550,8 +574,13 @@ void main() {
 
           completer.complete(42);
 
-          expect(sub.read().future, completion(21));
-          verifyZeroInteractions(listener);
+          expect(sub.read().future, completion(42));
+          final capture =
+              verifyOnly(listener, listener(captureAny, captureAny)).captured;
+
+          expect(capture.length, 2);
+          expect(capture.first, completion(21));
+          expect(capture.last, completion(42));
         });
 
         test('resolves with the new state when notifier.state is changed',

packages/riverpod/test/providers/future_provider/future_provider_test.dart

@@ -74,6 +74,33 @@ void main() {
     expect(container.read(autoDispose).value, 84);
   });
 
+  test('Does not skip return value if ref.state was set', () async {
+    final completer = Completer<void>();
+    final provider = FutureProvider<int>((ref) async {
+      await Future<void>.value();
+      ref.state = const AsyncData(1);
+      await Future<void>.value();
+      ref.state = const AsyncData(2);
+      await Future<void>.value();
+      completer.complete();
+      return 3;
+    });
+    final container = createContainer();
+    final listener = Listener<AsyncValue<int>>();
+
+    container.listen(provider, listener, fireImmediately: true);
+
+    await completer.future;
+    await container.pump();
+
+    verifyInOrder([
+      listener(null, const AsyncLoading<int>()),
+      listener(const AsyncLoading<int>(), const AsyncData(1)),
+      listener(const AsyncData(1), const AsyncData(2)),
+      listener(const AsyncData(2), const AsyncData(3)),
+    ]);
+  });
+
   test('supports family overrideWith', () {
     final family = FutureProvider.family<String, int>((ref, arg) => '0 $arg');
     final autoDisposeFamily = FutureProvider.autoDispose.family<String, int>(