file download actor

test/file_download_actor_test.dart

@@ -0,0 +1,84 @@
+import 'dart:io';
+import 'dart:typed_data';
+
+import 'package:http/http.dart' as http;
+import 'package:http/testing.dart';
+import 'package:swarm/swarm.dart';
+import 'package:test/test.dart';
+
+void main() {
+  late Directory tmpDir;
+
+  setUp(() async {
+    tmpDir = await Directory.systemTemp.createTemp('file_download_test_');
+  });
+
+  tearDown(() async {
+    await tmpDir.delete(recursive: true);
+  });
+
+  FileDownloadActor makeActor(http.Client client) => FileDownloadActor(
+        fileActor: FileActor(),
+        httpClient: client,
+      );
+
+  test('returns FileDownloaded with correct savePath', () async {
+    final client = MockClient(
+      (_) async => http.Response.bytes([1, 2, 3], 200),
+    );
+    final path = '${tmpDir.path}/output.bin';
+    final result = await makeActor(client).handle(
+      DownloadFile(url: 'https://example.com/file', savePath: path),
+    );
+    expect(result, isA<FileDownloaded>());
+    expect((result as FileDownloaded).savePath, equals(path));
+  });
+
+  test('saves correct bytes to disk', () async {
+    final bytes = Uint8List.fromList([0xDE, 0xAD, 0xBE, 0xEF]);
+    final client = MockClient(
+      (_) async => http.Response.bytes(bytes, 200),
+    );
+    final path = '${tmpDir.path}/data.bin';
+    await makeActor(client).handle(
+      DownloadFile(url: 'https://example.com/file', savePath: path),
+    );
+    expect(await File(path).readAsBytes(), equals(bytes));
+  });
+
+  test('sends GET request to the correct URL', () async {
+    http.Request? captured;
+    final client = MockClient((request) async {
+      captured = request;
+      return http.Response.bytes([0], 200);
+    });
+    await makeActor(client).handle(
+      DownloadFile(
+        url: 'https://example.com/assets/image.png',
+        savePath: '${tmpDir.path}/image.png',
+      ),
+    );
+    expect(captured!.method, equals('GET'));
+    expect(
+      captured!.url.toString(),
+      equals('https://example.com/assets/image.png'),
+    );
+  });
+
+  test('non-2xx response throws', () async {
+    for (final status in [400, 403, 404, 500]) {
+      final client = MockClient(
+        (_) async => http.Response.bytes([], status),
+      );
+      await expectLater(
+        makeActor(client).handle(
+          DownloadFile(
+            url: 'https://example.com/file',
+            savePath: '${tmpDir.path}/out.bin',
+          ),
+        ),
+        throwsA(isA<Exception>()),
+      );
+    }
+  });
+}