✅ Add tests

dio_test/lib/src/test/cancellation_tests.dart

@@ -113,5 +113,33 @@ void cancellationTests(
         ),
       );
     });
+
+    test(
+      'not closing sockets with requests that have same hosts',
+      () async {
+        final token = CancelToken();
+        final completer = Completer<Response?>();
+        // Complete the first request with the cancel token.
+        await dio.get('/get', cancelToken: token);
+        // Request the second without any cancel token, but with the same host.
+        dio.get('/drip?duration=3').then(
+          (res) {
+            completer.complete(res);
+            return res;
+          },
+          onError: (e) {
+            completer.complete(null);
+            return Response(requestOptions: (e as DioException).requestOptions);
+          },
+        );
+        // Simulate connection established.
+        await Future.delayed(const Duration(seconds: 1));
+        token.cancel();
+        final response = await completer.future;
+        // Response should be obtained without exceptions.
+        expect(response, isNotNull);
+      },
+      testOn: '!browser',
+    );
   });
 }