/posts-demo

An offline first Android application which shows a list of posts with comments using Kotlin, MVVM, Clean Architecture, RxJava, Retrofit, Jetpack & more 🔥

Primary LanguageKotlin

Post demo 📰🚀

Stack

  • 100% Kotlin
  • RxJava2
  • Jetpack navigation
  • Retrofit
  • Koin
  • Material
  • Room
  • MockK
  • Truth
  • Espresso

Architecture

Clean Architecture with MVVM

I used MVVM because of its benefits and the extended use since it’s part of Android Jetpack.

However, I’m a big fan of MVI since it works pretty good with user interfaces and reactive programming like RxJava or coroutines with Flow. I didn’t used it looking for simplicity since MVVM has a better learning curve and readability so will be easier to understand at first look for everyone.

Modules

I decided to just include a single module app separated by three packages which are the clean architecture layers (data, domain & presentation).

In other projects I’ve used multimode projects since it has a lot of benefits:

  • Faster build time
  • Conflicts reduction (related to work collaborations).
  • Re-usability
  • Feature encapsulation
  • Better dependencies management.
  • Team work collaboration between teams so you don’t need to rebuild the whole app just the module you touched.

Also thanks to buildSrc plugin the project handles the dependency much better than normal

However, I’ve decided to not use multimode on this project because of the next reasons:

  • over engineering
  • creating three modules (data, domain, presentation) should be the same as reason above and also distributed monolith which is not great IMO.

Data layer

First you could think we should create a repository for every entity following the repository pattern:

  • UserRepository
  • PostRepository
  • CommentRepository

However, Comment it’s an associated entity of Post so it makes no sense by its own. In conclusion, Post acts as an aggregate root.

Keeping in mind the aggregate root and we don’t need to interact with comment or user entities directly so I just created a single repository to handle the posts just exposing an API.

Tests

Unit tests

To run the tests just execute the next command

./gradlew test

Instrumentation tests (integration & UI)

To run instrumented tests just execute the next command

./gradlew connectedAndroidTest

Or you can execute ./run_instrumented_tests.sh which disables device animations and enables them when it finishes.

UI tests uses [Robot Pattern](Presentation: Testing Robots - Jake Wharton) in order to separate the what from the how in order to let QA write UI tests by themselves without needing to know about views nor Espresso.