Flutter Test MissingPluginException

If you're using shared_preferences 0.2.4 and above, use setMockInitialValues:

SharedPreferences.setMockInitialValues({}); // set initial values here if desired

For earlier versions you can do it manually:

const MethodChannel('plugins.flutter.io/shared_preferences')
  .setMockMethodCallHandler((MethodCall methodCall) async {
    if (methodCall.method == 'getAll') {
      return <String, dynamic>{}; // set initial values here if desired
    }
    return null;
  });

I had the exact same problem with the flutter_secure_storage plugin. I believe the issue is that with both plugins you are relying on storage on your phone or emulator (not something in your app) so it's not available in your test environment. Try running the test directly by executing flutter run your_test_file.dart. According to https://flutter.io/testing/ this should execute your test "in your preferred runtime environment such as a simulator or a device." It worked perfectly for me.