Fix: Resolve ListParam equality issue for caching identical requests (#…

…2366)

### What this PR does

Resolves #2364

This PR addresses an issue with ListParam equality, where identical
requests were not recognized as the same due to reference comparison of
lists. This caused multiple identical requests to be sent to the server,
even when caching was implemented.

### Changes introduced

Updated ListParam's operator == to use DeepCollectionEquality for proper
deep equality comparison of list contents.
Added relevant unit tests to validate the fix and ensure no regression.

dio/CHANGELOG.md

@@ -9,6 +9,7 @@ See the [Migration Guide][] for the complete breaking changes list.**
 - Removes redundant warnings when composing request options on Web.
 - Fixes boundary inconsistency in `FormData.clone()`.
 - Support `FileAccessMode` in `Dio.download` and `Dio.downloadUri` to change download file opening mode
+- Fix `ListParam` equality by using the `DeepCollectionEquality`.
 
 ## 5.7.0
 

dio/lib/src/parameter.dart

@@ -1,3 +1,5 @@
+import 'package:collection/collection.dart';
+
 import 'options.dart';
 
 /// Indicates a param being used as queries or form data,
@@ -26,9 +28,12 @@ class ListParam<T> {
       identical(this, other) ||
       other is ListParam &&
           runtimeType == other.runtimeType &&
-          value == other.value &&
+          const DeepCollectionEquality().equals(value, other.value) &&
           format == other.format;
 
   @override
-  int get hashCode => value.hashCode ^ format.hashCode;
+  int get hashCode => Object.hash(
+        const DeepCollectionEquality().hash(value),
+        format,
+      );
 }

dio/pubspec.yaml

@@ -21,6 +21,7 @@ environment:
 
 dependencies:
   async: ^2.8.2
+  collection: ^1.16.0
   http_parser: ^4.0.0
   meta: ^1.5.0
   path: ^1.8.0

dio/test/parameter_test.dart

@@ -0,0 +1,24 @@
+import 'package:dio/dio.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('ListParam', () {
+    test('param1 and param2 should be considered equal', () {
+      final param1 = const ListParam(['item1', 'item2'], ListFormat.csv);
+      final param2 = const ListParam(['item1', 'item2'], ListFormat.csv);
+      expect(param1 == param2, isTrue);
+    });
+
+    test('param1 and param3 should not be considered equal', () {
+      final param1 = const ListParam(['item1', 'item2'], ListFormat.csv);
+      final param3 = const ListParam(['item3', 'item4'], ListFormat.csv);
+      expect(param1 == param3, isFalse);
+    });
+
+    test('Order matters: param1 and param4 should not be equal', () {
+      final param1 = const ListParam(['item1', 'item2'], ListFormat.csv);
+      final param4 = const ListParam(['item2', 'item1'], ListFormat.csv);
+      expect(param1 == param4, isFalse);
+    });
+  });
+}