Add unit tests setup

[wzieba]

Description

This PR adds unit tests setup for the SDK. I decided to introduce Robolectric to be able to test AsyncTask API.

It also adds support for measuring codecoverage via kover plugin, as well as integration with Codecov: https://app.codecov.io/github/Parsely/parsely-android

Kotlin Gradle Plugin is added as I plan to write tests in Kotlin and it was established internally, that we'll aim to rewrite the SDK to Kotlin as well.

To merge after #77 is merged

How to test

CI should be enough: you could also run koverHtmlReportRelease task and see generated HTML report with 0% code coverage.

Kover report

[ParaskP7]

👋 @wzieba !

I have reviewed and tested this PR as per the instructions, everything works as expected, great job, let's start testing! 🌟 🎉 🌟

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This PR adds unit tests setup for the SDK. I decided to introduce Robolectric to be able to test AsyncTask API.

👍

It also adds support for measuring codecoverage via kover plugin, as well as integration with Codecov: https://app.codecov.io/github/Parsely/parsely-android

Awesome, thanks for that and for trying kotlinx-kover! 🥇

Kotlin Gradle Plugin is added as I plan to write tests in Kotlin and it was established internally, that we'll aim to rewrite the SDK to Kotlin as well.

👍

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I have left few suggestions (💡) for you to consider. I am going to approve this PR anyway, since none is blocking. I am NOT going to merge this PR yet to give you some time to apply any of my suggestions. However, feel free to ignore them and merge the PR yourself.

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EXTRAS

1. Minor (🔍): The testImplementation dependencies got added as part of this 915e4e8 commit. which was a bit off. I guess that was meant for that next a109e80 commit instead... 😅

[codecov]

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