Country Flags

Introduction

Android app that pulls data from https://restcountries.eu/rest/v2/all.

Used libraries

Dagger2 - Dagger2 was used for dependency injection.
RxJava2 - RxJava2 was used for threading and data stream management.
Retrofit2 - Network calls
AndroidKtx - For cool extensions to Android classes.
Architecture Components - For Lifecycle in the presentation layer.
Mockito - For mocking test dependencies.
JUnit - For Unit test assertions etc.
Konveyor - For generating random data for tests.
Espresso - For UI testing.

Process

I decided to use clean architecture and also break down the project into modules, I thought of exploring Kotlin Flows extensively but decided otherwise because RxJava2 is (as at the time of writing more mature for my chosen presentation architecture MVI), I also decided to use different models for each layer of the architecture so I could do some data cleaning and conversion to fit the models into each layer. I wrote interfaces to represent repositories in the domain layer and then wrote UseCases for searching countries and fetching all countries and then wrote tests for the usecases and repositories.

Afterwards I started writing the data layer, here I began by writing models for each of the apps entities/data objects and then interfaces that described classes that would interact with the restcountries API e.g ICountriesRemote. I then wrote concrete implementations of all the repositories defined in the domain layer with tests.

Finally I started work on the UI layer. I used the MVI architecture supported by ViewModel and RxJava2. I tested only the ViewModel classes and wrote a small navigation wrapper around the FragmentManager API to switch between destinations in the application and used Dagger2 to provide dependencies to the fragments and ViewModels.

Possible Improvements

I had a lot of fun building this. There are some improvements I intend to make.

• Write more tests for UI.
  
• Use MockWebServer to test Remote layer API calls.
  
• Improve UI and add a bookmarking feature (just because I can 🙂).
  
• Write more Unit tests.

Build Instructions

• Clone repository.
  
• Run with Android Studio 4.0 canary 3 and above.