Decouple asset loading logic from Localization

[spiritinlife]

Library shouldn't make assumptions about asset loading. For example the recent useDocumentStorage shouldn't be added as an option to EasyLocalizationDelegate since its very specific. Allowing the developer to bring their own asset loading logic is the only way to proceed safely.

We provide a default asset loader RootBundleAssetLoader and allow the developer to override this default. By doing this we also remove http dependency and the loadPath if/else logic.
In the example, I have provided asset loaders for Network, File, String, Testing and more can be added.

This also allows developers to do integration testing in their apps since this bug flutter/flutter#44182 right now is an issue for flutter_driver.

[danilofuchs]

I really like the approach you took.
It enables many more integration possibilities. Currently, the library assumes way too much responsibility when it comes to data fetching, with not much benefits.

Also fixes #38

[spiritinlife]

@danilofuchs We could also just expose load as function on the LocalizationDelegate instead of a class, wasn't sure whats best for this.

[spiritinlife]

@aissat @danilofuchs Loosing the dependency on rootBundle allows us to unit test localization.dart.
I have added some initial tests, take a look.
This could be a start for this #34

[aissat]

hi guys this great work, I agree with all code but I have a suggestion to make this code more simple and easy

• we must hide this code from main.dart

class StringAssetLoader extends AssetLoader {
  @override
  Future<String> load(String localePath) {
    return Future.value('''{"title" : "Hello"}''');
  }
}

class FileAssetLoader extends AssetLoader {
  @override
  Future<String> load(String localePath) {
    File file = File(localePath);
    return file.readAsString();
  }
}

class NetworkAssetLoader extends AssetLoader {
  @override
  Future<String> load(String localePath) async {
    String url =
        "https://raw.githubusercontent.com/aissat/easy_localization/master/example/$localePath";
    return http.get(url).then((response) => response.body.toString());
  }
}

// asset loader to be used when doing integration tests
// default AssetLoader suffers from this issue
// https://github.com/flutter/flutter/issues/44182
class TestsAssetLoader extends AssetLoader {
  @override
  Future<String> load(String localePath) async {
    final ByteData byteData = await rootBundle.load(localePath);
    return utf8.decode(byteData.buffer.asUint8List());
  }
}

i mean i'll make this in easy_localization PKG with keep others customizable
example :

import 'package:path_provider/path_provider.dart';
class FileProvidertLoade extends AssetLoader {
  @override
  Future<String> load(String localePath) {
       Directory appDocDir = await getApplicationDocumentsDirectory();
       String appDocPath = appDocDir.path+"localePath";
      .......
  }
}

[spiritinlife]

@aissat agree on this.
Maybe these AssetLoaders should be given as examples in Readme.md

[aissat]

@spiritinlife look last update

[aissat]

@aissat @danilofuchs Loosing the dependency on rootBundle allows us to unit test localization.dart.
I have added some initial tests, take a look.
This could be a start for this #34

thanks, @spiritinlife that's great work 👍 💯

[spiritinlife]

@aissat Thank you for your feedback and your awesome work. I checked your latest commits and added some comments.
I don't fully agree but i am ok with it :)
The gist of my comments is that we shouldn't provide any AssetLoader apart from RootBundleAssetLoader and we should drop the dependency to http since its unrelated to the package.

Example AssetLoaders should be provided in Readme so that the user knows how to proceed.
Also loadPath is very specific to NetworkAssetLoader and does not serve any other purpose, thus imho it should be removed completely.
Localization should get the Locale and the base resources path and call load with the proper localePath.

[aissat]

@spiritinlife I agree with u about NetworkAssetLoader and StringAssetLoader very logical