[HACK week] Product list - Add favorite product filter option

[selanthiraiyan]

Part of: #12274

Description

Start showing a new filter option in the product list filter screen.

The selection is persisted to storage and loaded again.

Changes

• Added new FavoriteProductsFilter filter for filtering favorite products.
• Store the favorite product filter to storage and load it from storage.
• Show the new filter option only if the feature flag is turned on.
• Update unit tests.

Steps to reproduce

Prerequisites

• Use a Woo store with more than 100 products.
• You can create a JN store and generate 100+ products using Woo Smooth generator.
• Using the smooth generator helps to generate products with different types, status and category. (Helps with testing filters)

Feature flag off

• Login into the app
• Navigate to Products tab
• Tap "Filter"
• Test by applying different filters
• Validate that the product filtering works as expected

Feature flag on

• Turn on the favoriteProducts feature flag by returning true from here
• Login into the app
• Navigate to Products tab
• Tap "Filter"
• Validate that you see the "Favorite Products" filter.
• Select the "Favorite Products" filter -> Switch to "Favorite Products" from "Any"
• Tap "Show Products"
• Validate that products are loaded correctly. (Actual filtering logic will be added in upcoming PRs)
• Kill the app
• Relaunch the app
• Navigate to Products tab
• Tap "Filter"
• Validate that the "Favorite Products" filter selection was persisted and reloaded from storage

Testing information

• Tested the product filtering works as before.
• Tested that the new favorite products filter is displayed upon turning on feature flag.

Screenshots

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

Reviewer (or Author, in the case of optional code reviews):

Please make sure these conditions are met before approving the PR, or request changes if the PR needs improvement:

• The PR is small and has a clear, single focus, or a valid explanation is provided in the description. If needed, please request to split it into smaller PRs.
• Ensure Adequate Unit Test Coverage: The changes are reasonably covered by unit tests or an explanation is provided in the PR description.
• Manual Testing: The author listed all the tests they ran, including smoke tests when needed (e.g., for refactorings). The reviewer confirmed that the PR works as expected on all devices (phone/tablet) and no regressions are added.

[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce iOS by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce iOS
	Build Number	pr13995-154eec1
	Version	20.5
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	154eec1
	App Center Build	WooCommerce - Prototype Builds #11019

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[hafizrahman]

I tested this both in off and on feature flag state, and in the on state I tested all the cases including by killing the app and returning. I can confirm that everything works fine. The code is also following the existing filtering logic, so all good.

Aside:

While looking at the Filter screen, since Favorite Product is inherently a boolean, I wonder if it's better UI-wise to make it a toggle, instead of navigating to another screen to select. It wil save time, at least.

That is unrelated to this PR, though.

[selanthiraiyan]

Thanks for the review.

While looking at the Filter screen, since Favorite Product is inherently a boolean, I wonder if it's better UI-wise to make it a toggle, instead of navigating to another screen to select. It wil save time, at least.

Good suggestion, Hafiz! Logged it as a subtask under enhancements #12274