Lista

Lista helps building composable sections and nested lists in RecyclerViews. It also comes with useful Espresso extensions that help you build UI tests that perform actions in lists.

Install

 implementation 'com.rubensousa.lista:lista:3.0.0'
 
 // Optional Espresso test extensions
 androidTestImplementation 'com.rubensousa.lista:lista-testing:3.0.0'

Basic Setup

1. Define a ListaSection. Example:

class CardSection : ListaSection<CardModel, CardSection.VH>() {

    override fun onCreateViewHolder(parent: ViewGroup): VH {
        return VH(inflate(parent, R.layout.section_card))
    }

    class VH(view: View) :  ListaSectionViewHolder<CardModel>(view) {

        private val binding = SectionCardBinding.bind(view)

        override fun onBound(item: CardModel, payloads: List<Any>) {
            super.onBound(item, payloads)
            binding.title.text = item.title
            binding.title.isVisible = item.showTitle
        }
    }

}

2. Create a ListaSectionRegistry like ClassSectionRegistry and register your sections:

val sectionRegistry = ClassSectionRegistry()
sectionRegistry.register(CardSection())

3. Create a ListaAdapter and assign the ListaSectionRegistry you created:

val diffItemCallback = object : DiffUtil.ItemCallback<SectionModel>() {

    override fun areItemsTheSame(oldItem: SectionModel, newItem: SectionModel): Boolean {
        return oldItem.getId() == newItem.getId()
    }

    override fun areContentsTheSame(oldItem: SectionModel, newItem: SectionModel): Boolean {
        return oldItem.equals(newItem)
    }

}

val adapter = ListaAdapter(diffItemCallback)
adapter.setSectionRegistry(sectionRegistry)

4. Use submit or submitNow to dispatch items to the adapter:

val adapterContentList = listOf(
    CardModel(title = "test", titleVisible = true)
)
adapter.submit(adapterContentList)

Nested lists

If you want to add a section that contains a nested list, you can extend your section from ListaNestedSection and/or your ViewHolder from ListaNestedSectionViewHolder

A ListaNestedSection contains a RecyclerView.RecycledViewPool for re-using ViewHolders across different lists and a ListaScrollStateManager to persist their scroll state.

class CardListSection : ListaNestedSection<CardListModel, CardListSection.VH>() {

    override fun onCreateViewHolder(parent: ViewGroup): VH {
        return VH(inflate(parent, R.layout.card_list))
    }


    class VH(view: View) : ListaNestedSectionViewHolder<CardListModel>(view) {

        private val binding = SectionCardListBinding.bind(view)
        private val adapter = ListaAdapter(ListModelDiffCallback())

        override fun onCreated() {
            super.onCreated()
            // Setup your RecyclerView here
        }

        override fun updateAdapter(item: CardListModel) {
            adapter.submitNow(item.list)
        }
        
        override fun getRecyclerView(): RecyclerView = binding.cardRecyclerView

        override fun getAdapter(): RecyclerView.Adapter<*> = adapter

        override fun getScrollStateKey(item: CardListModel): String = item.getId()

    }

}

GridLayoutManager span lookup

ListaSpanLookup can be used to provide different span sizes for each section.

First, create a ListaSpanLookup by passing the adapter and a default span size:

val layoutManager = recyclerView.layoutManager as GridLayoutManager
val spanSizeLookup = ListaSpanLookup(adapter, defaultSpanSize = layoutManager.spanCount)
layoutManager.spanSizeLookup = spanSizeLookup

Now you can register each span size with setSpanSizeForSection:

spanSizeLookup.setSpanSizeForSection(cardSection, 1)

Testing

The lista-testing artifact provides useful Espresso extensions for testing RecyclerViews.

Actions

ListaActions provides the following:

• smoothScrollTo - smooth scrolls a RecyclerView to a position
• waitForItemViewLayout - waits until a RecyclerView item view has been laid out

Assertions

ListaAssertions provides the following:

• withItemCount - asserts the item count of the adapter

Matchers

ListaNestedMatchers provides the following:

• withAscendant - matches a View with an ascendant that matches a Matcher
• withNestedRecyclerViewInSection - matches a RecyclerView inside a ViewHolder
• withNestedRecyclerView - similar to withNestedRecyclerViewInSection but assumes the RecyclerView is the ViewHolder's itemView.
• withNestedView - matches a View inside a nested RecyclerView
• withNestedChildView - matches a child View of a View that's inside a nested RecyclerView

Check the sample app for a complete example of integration of the library.

License

Copyright 2022 Rúben Sousa

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.