MobileDataUsageExercise

Android exercise, fetch open API data and show it in list and detail pages.

Task

fetch data from Singapore government open data
- the mobile data usage data, url pattern is https://data.gov.sg/api/action/datastore_search?resource_id=a807b7ab-6cad-4aa6-87d0-e283a7353a0f&limit=5&offset=6
show every year mobile data usage volume in a list
- the raw data is count by every quarter of year, like 2020-Q1
- show a dropdown image to show that at least one quarter volume is less than the last quarter
(optional) use data cache

Requirement

well designed
updated Android suite: kotlin, jetpack
well tested support by test framework

What will the app looks like

It will be two pages app, list and detail screen.

List page: show every year mobile data usage volume, can switch between normal style and card style.
Detail page: show one year usage, with the quarter data usage volume

structure

source code package

MainActivity
.volumelist : list page
.volumedetails : details page
.data : pojo define, fetch remote data and store in local sqlite
.util : constant define, tools etc

file tree

.
├── AndroidManifest.xml
├── java
│   └── com
│       └── yuman
│           └── anotherexercise
│               ├── MainActivity.kt
│               ├── ServiceLocator.kt
│               ├── VolumeApplication.kt
│               ├── data
│               │   ├── IVolumeRepository.kt
│               │   ├── QuarterVolumeItem.kt
│               │   ├── VolumeRepository.kt
│               │   ├── YearVolumeItem.kt
│               │   ├── local
│               │   │   ├── VolumeDao.kt
│               │   │   └── VolumeDatabase.kt
│               │   └── remote
│               │       ├── DataUsageResponse.kt
│               │       └── RemoteDataSource.kt
│               ├── util
│               │   ├── FetchDataStatus.kt
│               │   ├── StaticDefine.kt
│               │   └── VolleySingleton.kt
│               ├── volumedetails
│               │   └── VolumeDetailsFragment.kt
│               └── volumelist
│                   ├── VolumeListAdatper.kt
│                   ├── VolumeListFragment.kt
│                   └── VolumeListViewModel.kt
└── res
    ├── drawable
    │   ├── ic_launcher_background.xml
    │   └── ic_trending_down.xml
    ├── drawable-v24
    │   └── ic_launcher_foreground.xml
    ├── layout
    │   ├── activity_main.xml
    │   ├── fragment_volume_details.xml
    │   ├── fragment_volume_list.xml
    │   ├── switch_item.xml
    │   ├── volume_cell_card.xml
    │   └── volume_cell_normal.xml
    ├── menu
    │   └── main_menu.xml
    ├── mipmap-anydpi-v26
    │   ├── ic_launcher.xml
    │   └── ic_launcher_round.xml
    ├── mipmap-hdpi
    │   ├── ic_launcher.png
    │   └── ic_launcher_round.png
    ├── mipmap-mdpi
    │   ├── ic_launcher.png
    │   └── ic_launcher_round.png
    ├── mipmap-xhdpi
    │   ├── ic_launcher.png
    │   └── ic_launcher_round.png
    ├── mipmap-xxhdpi
    │   ├── ic_launcher.png
    │   └── ic_launcher_round.png
    ├── mipmap-xxxhdpi
    │   ├── ic_launcher.png
    │   └── ic_launcher_round.png
    ├── navigation
    │   └── nav_graph.xml
    └── values
        ├── colors.xml
        ├── strings.xml
        └── styles.xml

Unit Test

Restruct the project to support unit test, such as constructor injection to add test double, service locator to bypass singleton creation both in release and test environment.

to run test in console

./gradlew testDebugUnitTest --continue
./gradlew connectedDebugAndroidTest --continue

the report will be in folder: ./app/build/reports/

to get test coverage report

./gradlew testDebugUnitTestCoverage

(need the device or emulator is connected)
the report will be in folder: ./app/build/reports/

3rd part library used

Compair with Our Android 2020 development stack, which list the common but modern libraries.

Static analysis utilities & build tools

Not used stand-alone lint tools above, just used Android Studio integrated one： ./gradlew lint

Networking

Retrofit
OkHTTP
Gson

For the purpose of practice, chose using Google's Volley without OkHttp. Actually Retrofit+OkHttp is common choice for me.

Persistence

Room
SQLDelight

Permissions

Dexter

No need in this project

User interface

some of them are no need in this project

Core components and other useful libs

emmm, crash reporter, performance tools or even logger tool should be included

Testing

Jetpack lib not mentioned

NOTE

When doing instrumentation tests in Android Studio, ~~it may fail with message below~~

java.lang.UnsupportedOperationException: Failed to create a Robolectric sandbox: Android SDK 29 requires Java 9 (have Java 8)

one solution is to set runtime JRE environment to Java 9 in Android Studio:
Run -> Edit Configurations... -> in popup window, select the Android JUnit test configuration, specify the JRE to new folder

Fixed by changing "targetSdkVersion 29" to "targetSdkVersion 28", it will avoid the problem above.
The reason is it will change to use older Robolectric lib, and it will not throw out exception just a warning.

TODO

refine build script
test coverage report
dev ops integration
more test: server connection mock, integration test UI check, monkey test etc
play with: paging, viewpage2 etc
maybe: i18n, separate landscape view, controller style

what is done

coding, the app is functionally workable
unit test and simple function test

mainly did everything in Android Studio IDE environment, so tested in limited environment

freshleaf/MobileDataUsageExercise