Testing

The Download Handler#

PickerServiceProvider takes a share callback in place of the platform share sheet, which a test cannot reach without a platform channel. Boot the provider by hand and record what it is asked to share:

import 'package:flutter_test/flutter_test.dart';
import 'package:magic/magic.dart';
import 'package:magic_picker/magic_picker.dart';
import 'package:share_plus/share_plus.dart';

void main() {
  late List<ShareParams> shared;

  setUp(() {
    MagicApp.reset();
    Magic.flush();
    shared = <ShareParams>[];
  });

  tearDown(() {
    LocalAdapterContract.downloadHandler = null;
  });

  test('boot installs the download handler', () async {
    expect(LocalAdapterContract.downloadHandler, isNull);

    await PickerServiceProvider(
      Magic.app,
      share: (ShareParams params) async => shared.add(params),
    ).boot();

    await LocalAdapterContract.downloadHandler!('/tmp/a.txt', 'report.txt');

    expect(shared.single.fileNameOverrides, <String>['report.txt']);
  });
}

share_plus is a dependency of this package, so add it to your own dev_dependencies when a test names ShareParams. To go through Storage.download, boot Magic with the provider in 'app': {'providers': [...]}; Magic.init reads path_provider, so mock its channel in setUpAll.

Resetting the Static#

LocalAdapterContract.downloadHandler is a static field. MagicApp.reset() and Magic.flush() do not clear it, so a handler installed by one test is still there in the next. Set it back to null in tearDown, as the sample above does.

Faking the Pickers#

Pick calls the platform singletons that image_picker and file_picker publish: ImagePickerPlatform.instance for images, camera and video, and FilePickerPlatform.instance for files, directories and the save dialog. A test replaces the instance with a fake that extends the platform interface and restores the original afterwards. Depend on image_picker_platform_interface and file_picker in dev_dependencies to name them. The package's own test/facades/pick_test.dart shows complete fakes of both.

Converting Files#

The conversions need no fake. Build a MagicFile by hand and convert it:

import 'package:flutter_test/flutter_test.dart';
import 'package:magic/magic.dart';
import 'package:magic_picker/magic_picker.dart';

void main() {
  setUp(() {
    MagicApp.reset();
    Magic.flush();
  });

  test('a MagicFile with a path wraps into an XFile', () {
    final file = MagicFile(
      path: '/tmp/photo.jpg',
      name: 'photo.jpg',
      mimeType: 'image/jpeg',
    );

    final XFile xFile = file.toXFile();

    expect(xFile.path, '/tmp/photo.jpg');
  });
}

This test runs on the VM, where toXFile is synchronous. It would not compile for the web, where the method returns a Future; run web tests with flutter test --platform chrome and await the result.

Related Documentation#

• Pick: the facade under test.
• XFile Conversion: the two extensions and their platform split.
• Download: the handler PickerServiceProvider installs.