Only scrolls to a newly added Category after immediately adding it (in Settings)

app/src/androidTest/java/com/willowtree/vocable/settings/EditCategoriesViewModelTest.kt

@@ -17,13 +17,17 @@ import com.willowtree.vocable.room.RoomStoredPhrasesRepository
 import com.willowtree.vocable.room.VocableDatabase
 import com.willowtree.vocable.utility.FakeDateProvider
 import com.willowtree.vocable.utility.StubLegacyCategoriesAndPhrasesRepository
+import com.willowtree.vocable.utility.VocableKoinTestRule
 import kotlinx.coroutines.test.runTest
 import org.junit.Assert.assertEquals
 import org.junit.Rule
 import org.junit.Test
 
 class EditCategoriesViewModelTest {
 
+    @get:Rule
+    val koinTestRule = VocableKoinTestRule()
+
     @get:Rule
     val mainDispatcherRule = MainDispatcherRule()
 
@@ -70,6 +74,70 @@ class EditCategoriesViewModelTest {
         )
     }
 
+    // TODO: CC - the following 4 tests are flaky due to the way refreshCategories() is implemented
+    @Test
+    fun  refreshing_categories_without_adding_new_category_remains_at_first_index() = runTest {
+        val vm = createViewModel()
+        vm.refreshCategories()
+
+        vm.liveLastViewedIndex.test {
+            assertEquals(0, awaitItem())
+        }
+    }
+
+    @Test
+    fun  adding_new_category_and_refreshing_once_flips_to_new_categorys_index() = runTest {
+
+        val vm = createViewModel()
+        vm.refreshCategories()
+
+        categoriesUseCase.addCategory("new category")
+        vm.refreshCategories()
+
+        vm.liveLastViewedIndex.test {
+            assertEquals(0, awaitItem())
+            assertEquals(7, awaitItem())
+        }
+    }
+
+    @Test
+    fun  adding_new_category_and_refreshing_twice_flips_to_first_index() = runTest {
+        val vm = createViewModel()
+        vm.refreshCategories()
+
+        categoriesUseCase.addCategory("new category")
+
+        vm.refreshCategories()
+        vm.liveLastViewedIndex.test {
+            assertEquals(0, awaitItem())
+            assertEquals(7, awaitItem())
+        }
+
+        vm.refreshCategories()
+        vm.liveLastViewedIndex.test {
+            assertEquals(7, awaitItem())
+            assertEquals(0, awaitItem())
+        }
+    }
+
+    @Test
+    fun  adding_new_category_amongst_hidden_categories_and_refreshing_once_flips_to_last_non_hidden_index() = runTest {
+        val vm = createViewModel()
+        categoriesUseCase.updateCategoryHidden("preset_general", hidden = true)
+        categoriesUseCase.updateCategoryHidden("preset_basic_needs", hidden = true)
+
+        vm.refreshCategories()
+
+        categoriesUseCase.addCategory("new category")
+
+        vm.refreshCategories()
+        vm.liveLastViewedIndex.test {
+            assertEquals(0, awaitItem())
+            assertEquals(5, awaitItem())
+        }
+
+    }
+
     @Test
     fun categories_are_populated() = runTest {
         val vm = createViewModel()

app/src/main/java/com/willowtree/vocable/settings/EditCategoriesFragment.kt

@@ -7,6 +7,7 @@ import androidx.fragment.app.FragmentManager
 import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.lifecycleScope
 import androidx.lifecycle.repeatOnLifecycle
+import androidx.lifecycle.viewModelScope
 import androidx.navigation.fragment.findNavController
 import androidx.viewpager2.widget.ViewPager2
 import com.willowtree.vocable.BaseFragment
@@ -16,6 +17,7 @@ import com.willowtree.vocable.R
 import com.willowtree.vocable.databinding.FragmentEditCategoriesBinding
 import com.willowtree.vocable.presets.Category
 import com.willowtree.vocable.utils.VocableFragmentStateAdapter
+import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.launch
 import org.koin.androidx.viewmodel.ViewModelOwner
 import org.koin.androidx.viewmodel.ext.android.viewModel
@@ -121,15 +123,12 @@ class EditCategoriesFragment : BaseFragment<FragmentEditCategoriesBinding>() {
             }
         }
 
-        editCategoriesViewModel.lastViewedIndex.observe(viewLifecycleOwner) {
-            it?.let { index ->
-                val pageNum = index / maxEditCategories
-                // Wait until view pager has finished its layout
-                binding.editCategoriesViewPager.post {
+        editCategoriesViewModel.viewModelScope.launch {
+            editCategoriesViewModel.liveLastViewedIndex.collect {
+                val pageNum = it/maxEditCategories
                     if (isAdded && binding.editCategoriesViewPager.currentItem != pageNum) {
                         binding.editCategoriesViewPager.setCurrentItem(pageNum, false)
                     }
-                }
             }
         }
     }

app/src/main/java/com/willowtree/vocable/settings/EditCategoriesViewModel.kt

@@ -1,12 +1,12 @@
 package com.willowtree.vocable.settings
 
-import androidx.lifecycle.LiveData
-import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import com.willowtree.vocable.ICategoriesUseCase
 import com.willowtree.vocable.presets.Category
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
 
 class EditCategoriesViewModel(
@@ -15,8 +15,7 @@ class EditCategoriesViewModel(
 
     val categoryList = categoriesUseCase.categories()
 
-    private val liveLastViewedIndex = MutableLiveData<Int>()
-    val lastViewedIndex: LiveData<Int> = liveLastViewedIndex
+    val liveLastViewedIndex =  MutableStateFlow(0)
 
     private var overallCategories = listOf<Category>()
 
@@ -27,22 +26,25 @@ class EditCategoriesViewModel(
 
             overallCategories = categoriesUseCase.categories().first()
 
-            // Check if a new category was added and scroll to it
+            // Check if a new category was added and scroll to it only immediately after added
             if (oldCategories.isNotEmpty() && oldCategories.size < overallCategories.size) {
                 when (val firstHiddenIndex = overallCategories.indexOfFirst { it.hidden }) {
                     -1 -> {
-                        liveLastViewedIndex.postValue(overallCategories.size - 1)
+                        liveLastViewedIndex.update { overallCategories.size - 1 }
                     }
 
                     0 -> {
-                        liveLastViewedIndex.postValue(0)
+                        liveLastViewedIndex.update { 0 }
                     }
 
                     else -> {
-                        liveLastViewedIndex.postValue(firstHiddenIndex - 1)
+                        liveLastViewedIndex.update { firstHiddenIndex - 1 }
                     }
                 }
             }
+            else {
+                liveLastViewedIndex.update { 0 }
+            }
         }
     }