Issue/2630 display grouped products

[anitaa1990]

Part 1/3 of #2630. This PR adds logic to display products associated with grouped products.

Changes

• Added logic to display the product count for a grouped product, if the count > 0.
• Created a new fragment, module and View Model to handle the changes needed to show only the products for a specific grouped product.
• Split the ProductListViewHolder and ProductListDiffUtil to separate classes so that they can be reused by GroupedProductListAdapter as well as ProductListAdapter

Screenshots

. . .

Testing

• Click on a grouped product with atleast 2 associated products.
• Notice the grouped products section in the Product Detail screen.
• Click on the grouped products section and notice the list of products associated with this product, displayed correctly.
• Click on the delete icon for one of the items and verify:
  • that the "Done" menu button is displayed correctly.
  • that clicking on the back button displays the discard dialog.
• Click on the "Done" menu button and notice that
  • the "Update" button is displayed correctly in the Product detail screen.
  • the grouped products section displays the correct count.
• Click on the "Update" menu button and verify that the product is updated correctly.

Notes

• This PR is in draft till this FluxC PR can be reviewed and merged.
• The option to add a grouped product will take place in a subsequent PR.

Update release notes:

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[peril-woocommerce]

	Warnings
⚠️	PR has more than 500 lines of code changing. Consider splitting into smaller PRs if possible.

Generated by 🚫 dangerJS

[peril-woocommerce]

You can test the changes on this Pull Request by downloading the APK here.

[AmandaRiu]

@anitaa1990 Tried to test, but am getting this crash:

2020-08-17 16:57:01.147 30517-30517/com.woocommerce.android.dev E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.woocommerce.android.dev, PID: 30517
    java.lang.IllegalStateException: Gson().fromJson(groupedP… JsonElement::class.java) must not be null
        at org.wordpress.android.fluxc.model.WCProductModel.getGroupedProductIds(WCProductModel.kt:245)
        at com.woocommerce.android.model.ProductKt.toAppModel(Product.kt:548)
        at com.woocommerce.android.ui.products.ProductListRepository.getProductList(ProductListRepository.kt:141)
        at com.woocommerce.android.ui.products.ProductListViewModel$loadProducts$2.invokeSuspend(ProductListViewModel.kt:195)
        at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
        at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:56)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

[anitaa1990]

Hey @AmandaRiu!

Tried to test, but am getting this crash:

I'm not actually able to reproduce the crash. I tested with a branch new grouped product as well as existing product. But looking at the error, it seems to be that groupedProductIds is null (which shouldn't happen) but I added logic in FluxC to verify if the groupedProductIds is empty before parsing it. I opened a PR in FluxC as well.

Ready for another round 👍 Let me know if you are able to reproduce the crash. I would also like to reproduce, if possible so any testing steps would be helpful as well.

[AmandaRiu]

Just noting there is a TODO here for tracks events. Will that be handled in a separate PR? Same with a couple lines down.

[AmandaRiu]

Note: tracks event TODO.

[AmandaRiu]

Tested and looks good! 👍 Nice job Anitaa!