Convert test code to kotlin

[utzcoz]

1. Use Android Studio tool to convert test code to kotlin.
2. Fix null checking error, just adding !! and remove some ?.
3. Fix incompatibility of type between Int and Long in assert.

Test: ./gradlew test

Close #177

[codecov]

Codecov Report

Merging #179 (85fe1c2) into master (9977080) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #179   +/-   ##
=========================================
  Coverage     14.67%   14.67%           
  Complexity      442      442           
=========================================
  Files           125      125           
  Lines          8459     8459           
  Branches       1434     1434           
=========================================
  Hits           1241     1241           
  Misses         7062     7062           
  Partials        156      156           

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[utzcoz]

@farmerbb could you help to review this PR? Thanks.

[utzcoz]

The generated kotlin project by Android Studio uses test/java for kotlin test code, so I keep it.

[farmerbb]

Could you please change the variables in each test from private var to private lateinit var? That way we don't have to worry about overriding the null safety with !! when accessing these variables. I personally prefer to avoid using !! wherever possible, only using it as a very last resort.

[utzcoz]

Could you please change the variables in each test from private var to private lateinit var? That way we don't have to worry about overriding the null safety with !! when accessing these variables. I personally prefer to avoid using !! wherever possible, only using it as a very last resort.

The new commit processes it.

[utzcoz]

The new commit also rebases on master.

[farmerbb]

Thanks for doing that!

Do you happen to know how we can add Kotlin support to the main codebase while still being able to compile on Android-x86? I think it involves converting our Android.mk file to Android.bp, but I'm not sure how to go about doing that and I'm not setup to compile Android-x86.

[utzcoz]

Thanks for doing that!

Do you happen to know how we can add Kotlin support to the main codebase while still being able to compile on Android-x86? I think it involves converting our Android.mk file to Android.bp, but I'm not sure how to go about doing that and I'm not setup to compile Android-x86.

Yes, The Android.bp can do it. From AOSP 10, the SystemUI uses kotlin to write some logic, and its Android.bp can be an example. If we start to use Android.bp for kotlin, we will drop the support for Android-x86 pie for its later version. I know jon has worked with you to release Taskbar prebuilt apk for BlissOS, maybe it is the perfect solution for Android-x86's Taskbar release, and we can change all source code to kotlin after that.