fix(dio_web_adapter): stop timeout timers once the request has ended

plugins/web_adapter/CHANGELOG.md

@@ -2,7 +2,9 @@
 
 ## Unreleased
 
-*None.*
+- Stop the connect and receive timeout timers once a request has ended.
+  They stayed armed until they fired, keeping each request and its response
+  in memory for up to the configured timeout.
 
 ## 2.2.2
 

plugins/web_adapter/lib/src/adapter_impl.dart

@@ -262,9 +262,17 @@ class BrowserHttpClientAdapter implements HttpClientAdapter {
           options.onReceiveProgress!(event.loaded, event.total);
         }
       },
-      onDone: () => stopWatchReceiveTimeout(),
     );
 
+    // DOM event streams never close, so the timers must be stopped once the
+    // request ends (load, error, abort or timeout). An armed timer keeps the
+    // XHR and its response reachable until it fires.
+    web.EventStreamProviders.loadEndEvent.forTarget(xhr).first.then((_) {
+      connectTimeoutTimer?.cancel();
+      connectTimeoutTimer = null;
+      stopWatchReceiveTimeout();
+    });
+
     xhr.onError.first.then((_) {
       connectTimeoutTimer?.cancel();
       // Unfortunately, the underlying XMLHttpRequest API doesn't expose any

plugins/web_adapter/test/timers_test.dart

@@ -0,0 +1,42 @@
+@TestOn('browser')
+import 'dart:async';
+
+import 'package:dio/browser.dart';
+import 'package:dio/dio.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('no timeout timer stays active once the request has completed',
+      () async {
+    const connectTimeout = Duration(minutes: 3);
+    const receiveTimeout = Duration(minutes: 5);
+    final timers = <Timer>[];
+    final dio = DioForBrowser(
+      BaseOptions(
+        connectTimeout: connectTimeout,
+        receiveTimeout: receiveTimeout,
+      ),
+    );
+
+    // Record the timers armed by the adapter for this request.
+    final response = await runZoned(
+      () => dio.get<String>('data:text/plain,${'x' * 200000}'),
+      zoneSpecification: ZoneSpecification(
+        createTimer: (self, parent, zone, duration, callback) {
+          final timer = parent.createTimer(zone, duration, callback);
+          if (duration >= connectTimeout) {
+            timers.add(timer);
+          }
+          return timer;
+        },
+      ),
+    );
+    // `loadend` is dispatched right after `load`.
+    await Future<void>.delayed(const Duration(milliseconds: 50));
+
+    expect(response.data, hasLength(200000));
+    expect(timers, isNotEmpty, reason: 'the adapter armed its timeout timers');
+    // An armed timer keeps the XHR and its response reachable until it fires.
+    expect(timers.where((timer) => timer.isActive), isEmpty);
+  });
+}