From 8e953520273e3d6ff906b6aa11230a570fddaad5 Mon Sep 17 00:00:00 2001
From: joshuakrueger-dfx <joshua@dfxai.local>
Date: Thu, 4 Jun 2026 00:35:39 +0200
Subject: [PATCH] fix(dashboard): guard pending-transactions emits against
 post-close StateError
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PendingTransactionsCubit fires an un-awaited fetch from its constructor and
emits the result (or [] on error) with no isClosed guard. If the cubit is
closed (page popped) before the fetch resolves, emit throws
'Cannot emit new states after calling close' — and the catch's emit([]) throws
again, uncaught. Guard both emits with isClosed.

Regression: test/screens/dashboard/pending_transactions_cubit_test.dart
("does not emit if closed before the fetch resolves")

Issue #657 — Part 3, finding #16.
---
 .../bloc/pending_transactions_cubit.dart      |  5 +++++
 .../pending_transactions_cubit_test.dart      | 21 +++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/lib/screens/dashboard/bloc/pending_transactions_cubit.dart b/lib/screens/dashboard/bloc/pending_transactions_cubit.dart
index 7db47c80..c34fc8b5 100644
--- a/lib/screens/dashboard/bloc/pending_transactions_cubit.dart
+++ b/lib/screens/dashboard/bloc/pending_transactions_cubit.dart
@@ -14,9 +14,14 @@ class PendingTransactionsCubit extends Cubit<List<TransactionDto>> {
   Future<void> _loadPendingTransactions() async {
     try {
       final transactions = await _transactionHistoryService.fetchPendingTransactions();
+      // The fetch is started in the constructor and not awaited, so the cubit
+      // can be closed (page popped) before it resolves. Guard the emit to avoid
+      // a StateError after close (issue #657 P3 #16).
+      if (isClosed) return;
       emit(transactions);
     } catch (e) {
       developer.log('Failed to load pending transactions: $e', name: '$PendingTransactionsCubit');
+      if (isClosed) return;
       emit([]);
     }
   }
diff --git a/test/screens/dashboard/pending_transactions_cubit_test.dart b/test/screens/dashboard/pending_transactions_cubit_test.dart
index 2564da29..dc9e61c9 100644
--- a/test/screens/dashboard/pending_transactions_cubit_test.dart
+++ b/test/screens/dashboard/pending_transactions_cubit_test.dart
@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:flutter_test/flutter_test.dart';
 import 'package:mocktail/mocktail.dart';
 import 'package:realunit_wallet/packages/service/dfx/models/transactions/dto/transactions_dto.dart';
@@ -36,6 +38,25 @@ void main() {
       expect(cubit.state, [tx1, tx2]);
     });
 
+    test('does not emit (no StateError) if closed before the fetch resolves '
+        '(issue #657 P3 #16 regression)', () async {
+      final completer = Completer<List<TransactionDto>>();
+      when(() => service.fetchPendingTransactions())
+          .thenAnswer((_) => completer.future);
+
+      final cubit = PendingTransactionsCubit(service);
+      // Close while the constructor-started fetch is still in flight.
+      await cubit.close();
+
+      // Resolving now would, without the isClosed guard, emit after close and
+      // throw 'Cannot emit new states after calling close'.
+      completer.complete([_StubTx()]);
+      await Future<void>.delayed(Duration.zero);
+
+      // No exception escaped; the closed cubit kept its last state.
+      expect(cubit.isClosed, isTrue);
+    });
+
     test('falls back to an empty list when the service throws', () async {
       when(() => service.fetchPendingTransactions())
           .thenAnswer((_) async => throw Exception('network'));