fix: Use unique tmp location for each AudioCache (#1724)

# Description

There are conflicts on writing to the same location of the temporary
file path, when loading assets. This should be differentiated anyways as
two individual AudioCaches should not share the same cache location.

Closes #1424

packages/audioplayers/lib/src/audio_cache.dart

@@ -7,6 +7,9 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart' show rootBundle;
 import 'package:http/http.dart' as http;
 import 'package:path_provider/path_provider.dart';
+import 'package:uuid/uuid.dart';
+
+const _uuid = Uuid();
 
 /// This class represents a cache for Local Assets to be played.
 ///
@@ -45,7 +48,14 @@ class AudioCache {
   /// crucial).
   String prefix;
 
-  AudioCache({this.prefix = 'assets/'});
+  /// An unique ID generated for this instance of [AudioCache].
+  ///
+  /// This is used to load a file into an unique location in the temporary
+  /// directory.
+  String? cacheId;
+
+  AudioCache({this.prefix = 'assets/', String? cacheId})
+      : cacheId = cacheId ?? _uuid.v4();
 
   /// Clears the cache for the file [fileName].
   ///
@@ -89,7 +99,7 @@ class AudioCache {
     final byteData = await loadAsset('$prefix$fileName');
 
     // create a temporary file on the device to be read by the native side
-    final file = fileSystem.file('${await getTempDir()}/$fileName');
+    final file = fileSystem.file('${await getTempDir()}/$cacheId/$fileName');
     await file.create(recursive: true);
     await file.writeAsBytes(byteData.buffer.asUint8List());
 

packages/audioplayers/test/audio_cache_test.dart

@@ -8,7 +8,7 @@ import 'package:flutter_test/flutter_test.dart';
 class FakeAudioCache extends AudioCache {
   List<String> called = [];
 
-  FakeAudioCache({super.prefix});
+  FakeAudioCache({super.prefix, super.cacheId});
 
   @override
   Future<Uri> fetchToMemory(String fileName) async {
@@ -55,5 +55,19 @@ void main() {
       await cache.clear('audio.mp3');
       expect(cache.loadedFiles, <String, Uri>{});
     });
+
+    test('Use different location for two audio caches', () async {
+      const fileName = 'audio.mp3';
+      final cacheA = FakeAudioCache(cacheId: 'cache-path-A');
+      await cacheA.load(fileName);
+      expect(cacheA.loadedFiles[fileName]?.path, '//cache-path-A/audio.mp3');
+
+      final cacheB = FakeAudioCache(cacheId: 'cache-path-B');
+      await cacheB.load(fileName);
+      expect(cacheB.loadedFiles[fileName]?.path, '//cache-path-B/audio.mp3');
+
+      await cacheA.clearAll();
+      await cacheB.clearAll();
+    });
   });
 }